Metrication in the United Kingdom

Eurostar - The maximum speed in the design specification said "300 km/h", but some British newspapers quote it as "186 mph".

Metrication is the process of introducing metric units for measurement. Although the first recorded proposal for a decimal system of measure was made by a John Wilkins, a Briton, in 1668 and the adoption of metric units had been discussed regularly by Parliament since 1818, the formal policy of metrication only started in 1965.

In its accession treaty to the European Economic Community, the United Kingdom agreed to drop the use of non-metric units for selling goods by 1978. By 1980 most pre-packaged goods were sold by metric measure, but the mandatory use of metric units for packaged goods only took effect in 1995. Mandatory metric measures for goods sold loose or from bulk began in 2000. The use of "supplementary indications" (Imperial units given alongside the metric) was originally permitted for a limited period only, but that period was extended a number of times. In 2007, rather than extend the cut-off date for the use of supplementary units again, the EU announced that supplementary units could be used indefinitely. Informal usage of Imperial units remains widespread among people of all ages and the media, particularly for describing body measurements. In mathematics, school pupils are taught "rough metric equivalents of imperial units still in daily use", but are not taught how to manipulate Imperial units.

Current usage

File:UKproducts-metricusage.JPG

An example of metrication of UK consumer products. Two of the four items are in rounded metric amounts. The milk is labelled "1.136 litres (2 pints)" and the sausages are labelled "340 g (12oz)"

The UK currently uses rounded metric units for many purposes and rounded Imperial units for others.

Daily life

Petrol has been sold in litres since the 1980s but fuel consumption is quoted in miles-per-gallon and news reports still occasionally refer to fuel prices in pounds-per-gallon. (See additional information on road signs, below.) Weather reports on radio and television give temperatures in degrees Celsius, with rough conversions into degrees Fahrenheit for unusually high or low temperatures. Snow- and rainfall are reported in millimetres (often with a conversion into inches) and wind speeds in miles-per-hour (with rough conversions to kilometres-per-hour in certain regions). Speedometers have been given dual English-metric units for many years, and metric units are increasingly seen on signs indicating distances in metres.

Goods and retail

While most pre-packed food is entirely metric with no Imperial units shown, some pre-packed food have Imperial units as supplementary indicators and a few are in Imperial with metric supplementary indicators. Most supermarkets sell loose products with Imperial information as "supplementary indications" but Asda has now phased out such indications completely. While several food items continue to be packaged and sold in sizes based on the pound or ounce, most manufacturers display only the metric weight on the label (usually 113, 227, 340, 454 and 907 grams – equivalent to 4, 8, and 12 ounces and 1 and 2 pounds respectively). Items include jam, marmalade, honey, dates, British strawberries (especially when in season), sausages, beefburgers, fresh coffee and Christmas puddings. Crisps are normally sold in metric but some are now sold in ounces with metric shown in brackets.

Major supermarkets continue to sell milk in 1, 2, 4 and 6-pint plastic bottles: here the Imperial volume is shown on the label, alongside the equivalent metric volume. Other shops, such as newsagents and convenience stores, now tend to sell milk in smaller bottles based on the litre. Most supermarkets now sell cream in metric containers e.g. 600 ml (21.12 fl oz) instead of 568 ml (1 pint) but brands and small retailers vary. Tesco continues to provide Imperial indications on its metric cream packs and Marks and Spencer sells cream in Imperial sizes.

Malt vinegar still tends to be sold in 568 ml and 1.14 litre bottles, without reference to the Imperial pint.

Draught beer and cider are the only goods that may not be sold in metric units in the United Kingdom; the only legal measures for these drinks when sold on draught are 1⁄3 pint (190 ml) (rarely encountered), 1⁄2 pint (284 ml) and multiples of the latter. Bottled beer is most often sold in fractions of a litre but pint bottles are not rare. Milk sold in returnable bottles may by law be sold by the pint.

Cosmetics and toiletries are often dual labelled in metric units (grams or millilitres) and U.S. customary units (ounces or U.S. fluid ounces); this is standard practice throughout the world for goods intended for importation to the United States, where dual labelling is compulsory. Clothing is usually sold and marketed in inches and UK sizes, with the centimetre dimensions and continental size increasingly shown alongside the Imperial, with equal prominence.

Imperial indications were deleted on most electric kettles sold in Britain some years ago, but most still have a capacity of 1.7 litres (3 Imperial pints).

Legal requirements

Since 1 January 2000, all loose goods sold by reference to units of quantity must, by law, be weighed and sold using metric units, but other units may be displayed as "supplementary indications", providing the metric indication is "the more prominent, the imperial indication being, in particular, expressed in characters no larger than those of the metric indication."

Non-metric units, allowed by UK law for economic, public health, public safety or administrative use from 1 January 2000, are limited to:

• the mile (1.609 km), yard (91.44 cm), foot (30.48 cm) and inch (2.54 cm) for road traffic signs, distance and speed measurement,
• the pint (568 ml) for the dispensing of draught beer and cider, and for the sale of milk in returnable containers,
• the troy ounce (~31 g) for transaction in precious metals.

Goods and services sold by a description are not covered by weights and measures legislation. Thus, a fence panel sold as "6 foot by 6 foot" is legal, as is a 6 x 4 inch photograph frame, but a pole sold as "50 pence per linear foot" (with no accompanying metric price) would be illegal. There is no schedule to change road signs and speed measurement in cars to metric measures. On 23 February 2006 Alistair Darling, then Secretary of State for Transport, confirmed on the BBC Question Time programme that the Government had abandoned its previously long-standing plans to convert the UK's 2 million road signs to metric, purely on the grounds of cost.

National Health Service

On 25 February 2010, concern was expressed in the House of Lords at the continued use of Imperial units for weighing patients in National Health Service hospitals and facilities. Drug doses for patients are now worked out on their weight in kilograms, so using Imperial or switchable scales is a risk to the patients. The British Government announced it was taking steps to remedy this situation and insist that all NHS facilities complied with the requirement that all weighing scales displayed only metric units.

Public administration and journalism

The approach taken to metrication by writers in various parts of British society varies considerably. The civil service is bound by law to follow EU directives relating to public administration while journalists are not bound by such restrictions.

Newspapers have differing styles. For example, while both The Guardian' and The Times prefer metric units in most circumstances, and both provide exceptions where imperial units are preferred, they differ on some details.

The Times specifies that heights and weights put Imperial measures first while the Guardian's examples are from metric to Imperial. Similarly, while both give first place to hectares, the Guardian prefers square kilometres (with square miles in brackets) while the Times prefers square miles. Both retain the preference for the mile in expressing distances. In contrast, The Economist prefers metric units for "most non-American contexts," except for the United States section where "you may use the more familiar measurements." However, The Economist also specifies "you should give an equivalent, on first use, in the other units".

These rules of style have led to inconsistencies between administrative documents and the resulting news reports. Examples include:

• On 18 March 2005 Johnson Beharry was awarded the Victoria Cross for valour while serving in Iraq. The official citation included the text "...drive the vehicle through the remainder of the ambushed route, some 1500m long". The BBC, in paraphrasing the citation, used the expression "He guided the column through a mile of enemy ground".
• The Channel Tunnel Rail Link carries traffic from the Channel Tunnel to London. Government reports cited the design speed on the link as being 300 km/h while the BBC cited speeds of 186 mph.

The units of measure used on web pages associated with the British monarchy are a microcosm of the way in which Britain uses units of measure. For instance, the Jubilee Walkway Trust worked out a 60 km walking path to commemorate the Queen's diamond jubilee (and the Olympic Games) in 2012. The official website describing the royal residences (URL: .royal.gov.uk - the government website) and the Prince's Rainforests Project (which is scientifically-oriented) use metric units. However, the “private” websites (URL: .co.uk or .com) describing Balmoral Castle and the Sandringham estate use miles for distances and hectares for areas.

Road signs

See also: Road signs in the United Kingdom

A British speed limit sign indicating 30 mph.

File:A38DriverLocationSign km415.jpg

Driver location sign, and post, both indicating 415.0 kilometres

Road signs in Great Britain are regulated by Traffic Signs Regulations and General Directions 2002 (TSRGD) which requires linear units of measure to be in miles, yards, feet and inches. Weight limits are expressed in tonnes and, despite the fact that "T" is the recognised symbol for teslas, the legislation permits either "T" or "t" to be used as the symbol for "tonnes". Speed limits are in miles per hour, but no units are shown on the signs. On the UK motorway network, signs display distances in miles (often using the character "m" as a symbol. This conflicts with the metric system where "m" is the symbol for metre). Advance warnings are often given in yards, but the actual distance is the equivalent number of metres

In 2002 the legislation relaxed the "Imperial only" rule for height, width and length warning and prohibition signs and permitted such signs to display metric "supplementary indications". On 9 April 2010, further legislation made it mandatory to use dual units on height and width warning and restriction signs. This was because

"approximately 10 – 12% of bridge strikes involved foreign lorries. This is disproportionately high in terms of the number of foreign lorries on the road network." (Paragraph 53 of the Impact Analysis)

Since the late 1970s, British roads have been designed using metric units. Location marker posts were erected at 100-metre intervals on the hard shoulder giving the distance from a notional reference point in kilometres to enable maintenance workers, emergency services and the like to pinpoint specific points on the motorway. The digits on these posts were barely visible to motorists. This number was also encoded into the emergency phones that could be used by stranded motorists. The advent of the mobile phone meant that the location of motorists could no longer be pinpointed by reference to the emergency telephone that they were using. To enable such motorists to communicate with the emergency services, driver location signs were erected at approximately 500-metre intervals in 2007. These signs replicate the distances shown on the smaller location marker posts though no units are shown.

Railway systems

An 1845 Act of Parliament fixed British rail gauges at 4 ft 8.5 in and Irish rail gauges at 5 ft 3 in. The 4 ft 8.5 in gauge was the basis of 60 % of the world's railways, but is expressed as 1435 mm (including the United Kingdom) - a decrease of 0.1 mm, but well within the engineering tolerances. The Irish 5 ft 3 in gauge is now referred to as a 1600 mm gauge – the difference between the metric and imperial values being 0.2 mm, again well within engineering tolerances.

Rolling stock likewise is designed using metric units as it is required to meet the loading gauge requirements. (The British loading gauge is specific to Britain). However, track distances and speeds of most of Britain’s rail network are still shown in miles and chains and speeds in mile per hour, though metric units are used on the London Underground. Metric units are used throughout for engineering purposes, particularly on new and refurbished railway lines including the Channel Tunnel Rail Link, Tyne and Wear Metro, and Croydon metro.

Other exceptions

Other exceptions, common to many other countries, include aviation, shipping and rail transport – for example, the foot for aircraft altitude, nautical miles and knots – some of which are non-SI units, but accepted for use with SI.

The metric system is now used in the majority of industries. Clothing usually has dual labelling, but shoes are most often seen with traditional British sizes (though the Paris point sizes (exclusively) are not rare). Dual measures are often seen in the home entertainment and computer markets, for describing television, digital camera and monitor screen sizes. (The imperial size given for CRTs is typically that of the tube, whereas the metric measure – tagged 'vcm' – is that of the visible screen excluding the bezel). Products that may appear to be Imperial are actually manufactured to metric specifications, using metric drawings and made on metric machines, even if references to Imperial units persist in some areas. The coopers' trade is one of the exceptions to this rule.

Advocacy groups

Groups such as the British Weights and Measures Association and Active Resistance to Metrication (ARM) are actively opposed to metrication in the UK. In 2005, these activists claimed success against York City council's erection of 30 hiking trail signs with kilometre distance markings. Conceding that the law did not authorise them, the council agreed to cover the metric markings with plastic discs. ARM supporter Peter Rogers said: "Each time we are successful [in getting metric signs changed], it is a small but significant step towards eradicating them from our country. The Imperial weights and measures of this country are part of our traditions and part of our culture. The attempt to impose metric signs is one by stealth and deception and has been going on for many years." A Council spokeswoman said: "This was a genuine error and as soon as it was brought to our attention, we took measures to amend it. Giving information on a footpath sign such as the distance and destination is discretionary and we thought the public would appreciate this extra detail. The Ordnance Survey maps that we use to measure the footpaths are metric and the walk packs that we sell describe walks in kilometres, so it made sense to the officer who ordered the signs to give corresponding information."

A pro-metric group, the UK Metric Association, summarised the situation as "British weights and measures are in a mess. This is because although many aspects of national life are metric (including most industry and building, school mathematics and science, athletics, rugby union and Ordnance Survey maps), many imperial relics remain (e.g. in road signs, football commentaries, estate agents' advertisements and most non-specialist media)."

History

Before 1799

When James VI of Scotland inherited the English throne in 1603, England and Scotland had different systems of measure. This situation was continued for another century even though, in 1670, John Wilkins, the first president of the Royal Society, published his proposal for a metric system of measure. In 1707, under the Act of Union, the Parliaments of England and Scotland were merged and the English units of measure became the standard for the United Kingdom.

Although British inventor James Watt called for the creation of a global measurement system in 1783, a letter of invitation in 1790 from the French National Assembly to the British Parliament to help create such a system received no reply. The French continued alone and created the foundations of what is now called Système International d'Unités and is the sole measurement system for most of the world.

1799 to 1945

In 1799 the French adopted the metre and the kilogram as their new units of length and mass. As use of the new system, originally called the "Decimal System", grew through Europe, pressure grew in the UK for decimalisation. The issue of decimalisation of measurement was intertwined in the UK with decimalisation of currency. The idea was first discussed by a Royal Commission that reported in 1818 and again in Parliament by Sir John Wrottesley in 1824. Another Royal Commission was set up 1838 by Chancellor of the Exchequer Thomas Spring Rice and it reported in 1841 that decimal coinage was required first. A third commission advocated in 1853 decimal coinage in the form £ : 10 florin : 100 cent : 1000 mil. The first florins (one tenth of a pound sterling) were struck in 1849 as silver coins weighing 11.3 grams and having a diameter of 28 millimetres. In the London Tavern on Bishopsgate St. 1854 Sir John Wrottesley set up the "Decimal Association" in order to lobby for decimalisation of both measurement and coinage. Sir John met with Gladstone a few days later but was unable to win him to the idea. In 1862, the Select Committee on Weights and Measures favoured the introduction of decimalisation to accompany the introduction of metric weights and measures. A further Royal Commission "on the question of the introduction of metric system of weights and measures" also reported in 1869.

On the legal front, 1864 saw a Private Member's Bill pass which legalised use of the metric system in contracts. However, ambiguous wording of the 1864 law meant that traders who possessed metric weights and measures were still liable to arrest under Acts 5 and 6 William IV c63.

In 1875 the British delegation was one of twenty national delegations that attended a convention in Paris which resulted in seventeen of the nations signing the Metre Convention on 20 May 1875 which resulted in the setting up of the three bodies: the CGPM, CIPM and BIPM that were charged with overseeing weights and measures on behalf of the international community. The United Kingdom was one of the countries that declined to sign the convention. In 1882 the British firm Johnson, Matthey & Co secured an agreement with the French government to supply 30 standard metres and 40 standard kilograms. Two years later the United Kingdom signed the treaty and the following year it was found that the standard yard which had been in use since 1855 had been shrinking at the rate of one part per million every twenty years. In 1889 one of the standard metres and one of the standard kilograms that had been cast by Johnson, Matthey & Co were selected at random as the reference standard and the other standards, having been cross-correlated with each other were distributed to the signatory nations of the treaty.

In 1896 Parliament passed the Weights and Measures (Metric System) Act, legalising metric units for all purposes but not making them compulsory.

The situation was clarified in 1897 following another Select Committee which also recommended that metrication become compulsory by 1899. In 1904, scientist Lord Kelvin led a campaign for metrication and collected 8 million signatures of British subjects. Two years previously an Empire conference decided that metrication should be compulsory across the British Empire. On the opposition side, 1904 saw the establishment of the British Weights and Measures Association for "the purpose of defending and, where practicable, improving the present system of weights and measures". At this time 45% of British exports were to metricated countries. Parliament voted to set up a Select Committee on the matter.

This Select Committee reported in 1907 and a bill was drafted proposing compulsory metrication by 1910, including decimalisation of coinage. The opposition declared that decimalisation of coinage would cost £100m alone.

1945 to 1973

The matter was dropped in the face of wars and depression, and would not be again raised until the 1951 Hudgson Report, the result of yet another Select Committee.

The Hudgson Report recommended compulsory metrication and currency decimalisation within 10 years. It said "The real problem facing Great Britain is not whether to adhere either to the Imperial or to the metric system, but to maintain two legal systems or to abolish the Imperial." The report also recommended that the change should be done in concert with the Commonwealth (former Empire) and the USA. It also pointed out that metric standards were more accurate than Imperial ones, and that the yard and pound should be pegged to definite metric values. This was done by international agreement in 1959 and currently the yard is defined as 0.9144 metres exactly, and the pound as 0.453 592 37 kg exactly. Agreement could not be reached on the pint (and gallon), and this value still differs between the UK and US (the only countries that maintain legal definitions of these units).

File:Metrication-uk-logo.png

Metrication logo of the Board of Trade

In 1965 the Board of Trade and the Confederation of British Industry declared their full support for metrication and decimalisation. Currency decimalisation finally took place on Decimal Day, 15 February 1971, although £1 did not change in value. The Metrication Board was set up in 1969. Unlike its South African and Australian counterparts which had mandatory powers, it only had an "advisory, educational and persuasive role". Metric units have been taught in UK schools since the late 1960s (and exclusively since 1974), and certain industries also converted or largely converted decades ago. For example the paper industry converted in 1970, and the construction industry between 1969 and 1972 – although certain products continue to be produced to with reference to Imperial trade names but made using metric dimensions in the factory; for example, a 13 mm thick plasterboard is still often called 'half-inch', even though the measurement is rounded to a convenient metric size and so is now only approximately half an inch thick.

Metric Britain logo, Metrication Board

A Commons debate in 1970 on the introduction of compulsory metrication ended in farce. The governing Labour party was then unpopular and the opposition Conservatives revolted on the issue. Examples include:

• Robert Redmond, MP "When I have travelled abroad and particularly on the Continent, I have noticed that people have on their desks calculating machines while we in Britain do the same sums in our heads."
• Henry Kerby, MP "this metric madness, this alien academic nonsense, introduced secretly through the back door by a bunch of cranks and the big business tycoons...and put into clandestine operation."
• Carol Mather, MP "I am led to the conclusion that comprehensive universal metrication is a bit of a nonsense... there is a gap between the millimetre and the metre, there is no centimetre...The kilo is too heavy for the housewife to carry and we know that in France and Denmark they use the old system of the pound."

The press reports on the debate, particularly those of The Daily Telegraph and The Times, were very favourable to the opinions of the Conservatives. Following the debate the projected deadlines for the phased metrication steps were delayed one by one. The original intention of metrication "in concert with the Commonwealth" backfired; Australia, New Zealand and South Africa all completed their metrication processes by 1980, the year that the Metrication Board was abolished as a cost cutting measure. (In contrast, the situation of metrication in Canada resembles that of the UK, except that all road signs were converted in the 1970s.) The last laws which restricted the sale of metricated goods were only removed in 1995; though it is still illegal to sell draught beer in metric units, which in 2002 led to an Austrian-themed pub being asked to stop selling beer by the half litre traditional German steins.

1973 onwards

Before the UK joined the European Community in 1973, the only units of measure that were legally defined were those pertaining to length, area, volume and "mass or weight" [sic].

When the UK joined the European Community (now the European Union) it was obliged to accept into its national law within five years all EEC directives that were then in force. This included directive 71/354/EEC. This directive catalogued units of measure that might be used and for "economic, public administration, public health or public safety purposes". It also catalogued those units whose use was permitted only until the end of 1977. For many EU countries, these directives meant dropping the pfund, livre, pond, etc., in favour of "500 g", but in the case of the United Kingdom and the Republic of Ireland it meant the completion of their metrication programs which in the case of the United Kingdom had been under way since 1965. It also required the United Kingdom to formally define a number of other units of measure including those for electric current (ampere), electric potential difference (volt), temperature (degree Celsius and kelvin), pressure (pascal), energy (joule), power (watt) and so on.

European law requires the UK government to eliminate almost all non-metric units when used for goods and services sold by quantity by 31 December 2009. However, the Department of Trade and Industry recently announced that, "the Government intends to support the continued use of supplementary indications after 2009 for an indefinite period" – this appeared to indicate that the British Government was in favour of obtaining an indefinite derogation on the use of dual metric/Imperial markings. On 10 September 2007 the European Commission published a proposed amendment to EU Directive 80/181/EEC that would permit "supplementary indicators" to be used indefinitely.

Indecision and political opposition led the UK government to renegotiate this date first to 31 December 1989, then 1994, 1999 and recently to 31 December 2009. The involvement of the European Commission has led metrication to be linked in the public mind with euroscepticism, and the traditionally eurosceptic British press has taken a dim view of the process. Example stories include the Daily Star, which on 17 January 2001 claimed that beer would soon have to be sold by the litre. Today in the UK, bottled beer is most often sold in 500 ml bottles (and also 330 ml and 250 ml "stubbies"), though pint bottles are also available. Milk is most often sold by the pint, but 500 ml cartons are not unusual.

The European Union Units of Measurement Directive as amended by Directive 89/617/EEC required the UK government to pass laws in 1994 finally permitting the sale of goods using metric labelling, while permitting dual measurement. Public reaction to these regulations was negative . Such suspicion of externally-imposed change has long traditions; as Philip Grierson notes, the town of Lincoln paid "lavish" fines in 1201 rather than use government-imposed reformed weights and measures. Steve Thoburn applied to the European Court of Human Rights on the basis that his human rights had been violated but the court decided that no violation had occurred. George Gardiner of the Federation of Small Businesses called (without apparent response) for a civil disobedience campaign. In 1999 further laws were brought metricating the sale of, among other things, fresh fruit. The "Metric Martyrs" were shop owners that were fined for refusing to use metric units and for overcharging in response to metric customer requests.

In August 2005, the European Commission announced it would require Britain to set a legal deadline for the completion of metrication. However, on 9 May 2007, Industry Commissioner Günter Verheugen announced that the European Commission had dropped its plans to enforce the abolition of Imperial measures from 2010. This means that 'supplementary' imperial indications will be able to continue indefinitely alongside, but not instead of metric units after that date. Furthermore, in a letter to the British MEP Ashley Mote dated 5 June 2007, Commissioner Verheugen announced that in relation to the mile and the pint, "the Commission has no intention to endanger the historical and cultural traditions of Member States."

Costs

The estimated costs of metrication in the UK range from near zero to a 1970 estimate of £5bn (about £50bn in 2002 pounds) by opponents of the change. True scientific calculations of the potential costs have been fairly rare. A 2005 report pointed to the metrication of the UK's 2 million road signs as the major cost. In 2008/9, before the outcome of the consultations that led to the EU directive 2009/3/EC was known, the Department for Transport had a contingency of £746 million for the metrication of roads signs.

A 1970s study by the UK chemical industry estimated costs at £6m over seven years, or 0.25% of expected capital investment over the change period.

Some 90% of UK exports go to metric countries (as only Liberia, Burma and the United States have not adopted the International System of Units ), and there are costs to business of maintaining two production lines (domestic and exports to the US in Imperial and export in metric). These have been estimated at 3% of annual turnover by the Institute of Production Engineers, and at £1.1bn (1980) per annum by the CBI. Regardless of UK metrication, goods produced in the UK for export to the US would have still been labelled in non-metric units to comply with the US Fair Packaging and Labeling Act.

See also

• International System of Units
• Metrication opposition
• Imperial system

Bibliography

1. Grierson, Philip (1995). English Linear Measures: an essay in origins. 'The Stenton Lecture 1971', University of Reading.
2. McGreevy, Thomas (1995). The Basis of Measurement: Historical Aspects. Chippenham, Picton Pub. ISBN 0948251824.
3. McGreevy, Thomas (1997). The Basis of Measurement: Metrication and Current Practice. Chippenham, Picton Pub. ISBN 0948251840.
4. Linacre, Vivian T (2007). The General Rule. Butleigh : Squeeze. ISBN 1906069018.
5. Cairns, Warwick (2007). About the Size of It. London : Macmillan. ISBN 0230016286.

External links

• UK Government Department of Trade and Industry (policy statement)
• British Weights and Measures Association (anti-metric)
• UK metric association (pro-metric)