In today’s Sunday Telegraph, the columnist Simon Heffer calls for a return to the imperial system of measurement.  A similar article was written by Peter Hitchens in the Daily Mail and, more worryingly, Andrea Leadsom, the DEFRA secretary of state has called for imperial food labels.

As a qualified Inspector of Weights and Measures, I have spent the majority of my career dealing with the metric martyrs and the British Weights and Measures Association, the pressure group which wants the UK to only use imperial measures.  When the last element of the imperial system for trade was revoked, in 1999, I was at the heart of the metrication process.  I received personal abuse from imperial campaigners.  One of my colleagues received death threats.  It was ugly and thoroughly un-British.  My enforcement of weights and measures law reached the UK press, when a warning letter I sent to Tesco appeared on the front page of the Scottish Sun.  I had written to Tesco because they were involved in a ‘Save our Scales’ campaign.  They were marking products with imperial unit prices despite the fact that all their stores were already using metric measuring equipment.  Such activity was a criminal offence before the introduction of metric units for goods sold loose from bulk.

So, for the benefit of Messrs Hitchens and Heffer, and as advice to Mrs Leadsom, let’s set a few facts straight.

First, metrication has no link to the UK’s membership of the European Union.  It has been UK domestic policy to transfer to the metric system since the early 1960s, long before we entered the European Union.  In fact, the decision to go metric can be traced as far back as the middle of the 19th century.

In 1856, the United Kingdom was a signatory to the OIML treaty.  This was a worldwide treaty for the implementation of a single system of measurement for the entire world.  Virtually every sovereign state, including the United States of America, is a signatory to the OIML treaty.  The use of metric units for trade purposes became legal in Britain in 1875.

The real thrust of metrication began with Harold Wilson’s ‘white heat of technology’; his modernisation plan for the UK economy.  Wilson set up the UK metrication board with the aim of making the UK a metric country by the mid 1970’s.  That was in 1965, eight years before Edward Heath signed the UK into the EEC.

The metrication board took a sector by sector approach to replacing imperial units with their metric equivalents.  Science became metric almost immediately, quickly followed by the construction sector.  By 1979, the work of the metrication board was virtually complete.  As part of her ‘bonfire of the QUANGOS’ Margaret Thatcher abolished the metrication board.

In the mid-1980s pre-packed consumer goods went metric.  By 1997, and the Blair government, only goods sold loose from bulk were being sold in imperial measures.  New Labour announced it was to finish the work of Wilson and would complete the UK metrication programme.  In 2000, goods sold loose from bulk finally went metric.

The metrication order had specific exemptions for measuring road distances in miles, the sale of beer by the pint in pubs and for doorstep delivery milk.  It also allowed for unit prices and secondary indications of quantity in imperial units.  The only rule was that imperial quantity marks and unit prices must be less prominent than their metric equivalents.

The guidance on the statutory instrument clearly stated that consumers could continue to ask for imperial quantities and traders would have to supply the metric equivalent of the quantity requested.

It was planned that secondary imperial quantity markings would be removed from pre-packed goods by the mid-2000s.  This was the one element of metrication that was part of EU legislation.  The UK government successfully argued for the retention of secondary nominal quantity marks and the EU requirement was dropped.  So, for Mrs Leadsom’s information, pre-packed food can already be marked with imperial units and imperial unit prices for food sold loose from bulk are legal as long as they are accompanied by a metric unit price of equal prominence.

It has been 18 years since the UK went ‘fully metric’.  In that time, the metrological equipment manufacture and verification industry has dumped its imperial testing equipment.  Certificates of approval for imperial equipment have all lapsed.  Local Authorities no longer maintain imperial local standards, neither does the National Measurement Office.  Imperial units have not been taught in schools since the 1970s.

I estimate the cost of re-introducing the imperial system to local government will be between £150 million and £200 million.  The cost of reintroduction to industry and commerce could run to billions.

Then there is the effect of imperial measures on international trade.  Only two countries use imperial units, Myanmar (Burma) and the USA.  Myanmar uses the measures it had as a British colony before its international isolation.  it is rapidly converting to the metric system.  America uses its own imperial system which differs from Avoir Dupois.  For example, the US pint is 18 fluid ounces compared to the UK pint which is 20 fluid ounces.  This is because the early settlers to the US from the UK took old East Anglian measures to the US.  They left Britain before the system of measurement was properly enforced across the UK.  As with the measurement of time, it would take the industrial revolution to bring a consistent measurement across the whole of Britain.

As a result of the NAFTA trade agreement, prepackaged goods in the US are increasingly dual marked in both US imperial and metric units.  This is because both Canada and Mexico are metric countries.

I wrote to the department for Business, Energy and Industrial Strategy regarding Mrs Leadsom’s comments; the UK government ministry responsible for the UK measurement system.  I was assured that UK government policy remains that Britain will use a single system of measurement based on metric SI units but secondary imperial indications will remain in use.

So, the reintroduction of imperial could act as non-tariff trade barrier to 99.75% of the world; it adds significant costs to the UK economy and it is a system which is incomprehensible to 80% of the UK population.  It is also factual to state that the decision to go metric was in no way linked to the UK’s membership of the European Union.  It seems many on the Brexit right are confusing nostalgia with historical fact.  You may ask what they will demand next, perhaps the return of Calais and Aquitaine to UK rule?