Decimal currency, metric measures and the vanished link

For over a century, the introduction of metric measures in the UK was linked to that of decimal currency. But then, while we were saying farewell to £sd, the situation changed. We follow the story and draw an unsurprising conclusion.

John Wilkins in his Essay of 1668 made proposals for decimal weights and measures and for decimal currency, but he added, “I mention these particulars, not of any hope or expectation that the World will ever make use of them, but only to show the possibility of reducing all measures to one determined certainty.” We do not know if the English government became aware of his proposals; they certainly did not make use of them.

Russia was the first country in Europe to introduce decimal currency, early the eighteenth century, but it did not convert to decimal measures at that time. The newly-established USA followed at the end of the century.

So it was left to revolutionary France to be the first country to coordinate the reform of its currency and its measures.

In 1818, the UK Government appointed six Commissioners, including polymath Thomas Young,  to inquire ‘how far it might be practicable and advisable to establish a more uniform system of weights and measures.’ Mindful of recent events in France, their terms of reference did not include reform of the currency. The Commissioners reported in 1821, and the Imperial system of measures resulted.

This separation of currency from measures would not last.

In 1838, following the fire four years earlier at the Houses of Parliament that destroyed the standard pound and the standard yard, a Royal Commission for the Restoration of the Standards of Weight and Measure was set up. In its report, the Commission referred to ‘the advantage and facility of establishing in this country a decimal system of coinage’. It concluded that this was required before reform of weights and measures could be undertaken.

In 1854, Professor de Morgan, a prominent mathematician, was influential in setting up the Decimal Association to lobby for decimalisation of both measurement and coinage.

In 1857, a Royal Commission on Decimal Coinage was appointed. It concluded that it would not be right ‘to disturb the established habits of the people with regard to the coins now in use’ as long as the system of weights and measures remained unaltered.

In 1862, a Parliamentary Select Committee on Weights and Measures recommended that the Metric system be introduced and added that it felt it right ‘that a decimal system of money should, as nearly as possible, accompany a decimal system of weights and measures.’ It went on to say, ‘Both foreign and English witnesses think the maximum advantage can not be obtained without a combination of the two.’ A reference to its report appears in the previous article on Metric Views.

In 1869, the Standards Commissioners (yes, another Royal Commission) reported ‘on the question of the introduction of the metric system of weights and measures into the UK.’ The report was favourable and, although the question of the coinage was not within the Commissioners’ terms of reference, they nevertheless made the suggestion that the decimalisation of our system of coinage would be very useful to the public.

In 1904, scientist Lord Kelvin (he of the SI temperature scale) led a campaign for metrication and collected several million signatures. Parliament voted to set up a Select Committee on the matter. This reported in 1907 and a bill was drafted proposing compulsory metrication by 1910, including decimalisation of coinage. Nothing came of this.

Around fifty years later in 1959, a Joint Committee appointed by the British Association for the Advancement of Science, now the British Science Association, and the Association of British Chambers of Commerce concluded in its report entitled “Decimal currency and the metric system: should Britain change?” that there would be a 10 to 20 percent saving in mathematics teaching and a five percent overall saving in teaching time for children aged 7 to 11 years from changing both measures and currency.

In 1961, a Committee of Inquiry on Decimal Currency was appointed to look into the practicalities, and reported two years later. Interestingly, its chairman was an eminent scientist who would have understood the implications for the UK’s weights and measures of introducing decimal currency .

Finally, after receiving favourable reports from the British Standards Institution and the Federation of British Industry, now the CBI, the Government announced in May 1965 that they considered ‘it desirable that British industries on a broadening front should adopt metric units, sector by sector, until that system can become in time the primary system of weights and measures for the country as a whole.’ Within a year, the Government had announced the timetable for the introduction of decimal currency. ‘D day’ would be 15 February 1971. And the rest should now be history.

Alas, as we know, it is not.

Although ‘D day’ passed smoothly, doubts quickly appeared as to whether decimalisation of measures should automatically follow that of the currency. To provide reassurance, a White Paper was published in February 1972, setting out the case for metrication. But later in the same year, the Transport Minister announced that the metrication of speed limits and the changeover of road signs would not take place in 1973 as planned and that he had no alternative date in mind. Then in 1980, the Minister for Consumer Affairs indicated that the Government had given up on completion of a planned and orderly metric transition.

With the benefit of hindsight, it appears that departmental ministers were able take decisions regardless of the consequences for the wider economy, in particular for education.

From 1968, schools had begun to prepare for decimal currency and for metric weights and measures. Conversions required by £sd were dropped before ‘D day’, and those for miles, furlongs, chains, yards, feet and inches, and tons, hundredweights, quarters, stones, pounds and ounces, and gallons, quarts and pints followed soon after. Conversion using factors such as 3, 4, 8, 12, 14, 16, 20 and 22 disappeared from the classroom, never to return. Savings of time as foreseen in the BAAS/ABCC  report of 1959 were quickly reallocated within the curriculum.

Today we are all familiar with decimal currency, and over half of us have been taught the basics of metric measures at primary school. However, as predicted long ago, the areas of the economy still using Imperial measures are a source of confusion, waste and duplication, none more so than road traffic signs. For example, height and width restriction signs show feet and inches (designated by ‘ and “), but for many people conversion between these two units is a problem. Signs for distance display miles and yards using what appears to be a different system of units, but one that presents similar conversion problems. And if that were not enough for kids to get their heads round, “m” means “metre” when it appears on restriction signs but “mile”, that is about 1600 metres, when it appears on distance signs!

This and other issues related to education are tackled by Dr Metric in his booklet, “How big is an acre? No-one knows”, and on his web site: . Furthermore, the adverse consequences of the failure to complete the metric changeover are not limited to education and are discussed in UKMA’s publication “A very British mess”, available as a free download here: .

This account shows that our Victorian forebears gave much thought to the decimalisation of the currency and of weights and measures, and were aware of the benefits of linking the two. If they were able to observe today’s problems, they could be forgiven for saying ”We told you so.”

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4 Responses to Decimal currency, metric measures and the vanished link

  1. Erithacus says:


    One important correction. The decision to postpone indefinitely the metrication of road signs was announced to Parliament on 9 December 1970 (not 1972) - see this extract from Hansard: In fact it was the unexpected Conservative victory at the 1970 General Election that disrupted the whole conversion timetable and arguably is responsible for the current mess. Metrication had been opposed by a group of right wing Conservatives in the 1960s, and when the Heath Government took office in June 1970, they announced a review of the whole programme. John Peyton, Minister for Transport Industries (himself later a right wing candidate for Party Leader), then pre-empted the review by his crowd-pleasing announcement.

    In fact the 1972 White Paper (available at was not really a reassurance. Rather it was an attempt to find a compromise between the Conservative backwoodsmen and the demand from industry, retailers, engineering professions, teachers etc for a coordinated, smooth and rapid changeover. In order to square this circle it was decided that the changeover should go ahead but that it should be voluntary, industry by industry: "There will be no "M-Day" for metrication" (paragraph 12). Given the economic difficulties of the 1970s and the fact that the ensuing Labour Government had no or an insufficient majority, it was increasingly difficult to justify the cost - albeit modest - of converting the road signs.

    However, although the Conservative Government of 1970 bears the major responsibility for the debacle, the previous Labour Government also carries some blame. They failed to seek or secure a popular consensus for the changeover, failed to legislate to make it compulsory, there was no leadership from the top (i.e. Harold Wilson) and it was left to junior ministers and civil servants to manage as best they could without any legal backup or budget.

    To revert to the original theme of the article, whereas the decimalisation of the currency was properly planned (by the Treasury) with its own budget and legal timetable, metrication was unplanned, unco-ordinated and unbudgeted. It was therefore easy for the Luddites to disrupt it.

  2. Ezra Steinberg says:

    Sadly, it sounds like the UK approach to metrication was the exact opposite of the approach that Australia (and other countries) took.

  3. Sven G says:

    Anyway, decimal currency doesn't really conform to the SI specifications: for example, usually the monetary unit is divided into hundredths, while ideally it should be thousandths (as for the metre and millimetre); and the magnifying SI prefixes are rarely used: for example, G£, or gigapounds, instead of bn pounds.

    Ideally, there should be some further standardisation on this front, thus: maybe when there will be a global currency (or physical money will even be abolished, who knows...)?

    Australia, of course, remains the best example of full and fast metrication: the UK and US should really follow its example, and as soon as possible!

    But this would require both a forward looking "people" and "government" - which sadly doesn't seem to be the case, in today's (only apparently globalised and united) world...

  4. philh says:

    It is quite disgraceful that while schools and teachers are being lampooned for failures in education, the one direct step that the Government could take to genuinely improve the environment for the learning and application of mathematics (i.e. metricate road signs) they refuse to do!


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