Britain adopted the metric system in 1965.

Mostly.

How well has it worked? In 2015, 60% of eighteen- to twenty-four-year-olds didn’t know their weight in kilos; 54% didn’t know their height in centiwhatsits or in a combination of centiwhatsits and full-grown whatsits. For reasons I won’t pretend to understand, the slightly older group, twenty-five- to thirty-nine-year-olds, did better in both categories. After that, it went downhill.

For measuring short distances and for cooking, the number of people who use the metric system goes up. For long distances, though, people measure in miles. Well, why wouldn’t they? British roads are measured in miles,so folks drive in miles, regardless of how they measure walls.

All this–or the data part of it anyway–is from a YouGov poll. No one can say YouGov dodges the important issues. The poll also reports that the middle class is more likely to use metric measurements for short distances and for cooking than the working class is.

From this I gather that the upper class is too good to take surveys.

Most people you’ll find on hanging around on any random street corner on any random day won’t be frothing at the mouth about this, but you’ll find pro- and anti-metric advocacy groups and they do manage to keep themselves worked up enough to function. One anti- group argues for the inherent logic of feet and inches because the foot divides so neatly into quarters. So let’s take the argument seriously enough to look at how this eminently sensible system developed.

England emerged from the Dark Ages into the Middle Ages with a rich collection of measurements. Here’s a quick and highly incomplete survey. The data’s mostly from the Britannica and the link covers only a few bits of it. I could turn the whole post blue with Britannica links but one will get you into the general vicinity. You can to explore from there if you want it all.

The furlong started out as the length of a plowed furrow–a distance that would have varied from place to place and field to field. 

The rod varied from nine to twenty-eight feet and was sometimes called a perch or a pole.

An acre was the area that a yoke of oxen pulling a wooden plow could plow in one day. Predictably enough, that varied too.

The foot was initially based on the human foot–which you may have noticed isn’t a standard size. That’s why they don’t make one-size-fits-all shoes.

The mile was based on a Roman measurement, the mille passus, which was a thousand paces as measured by your average Roman legionary, who by the Middle Ages wasn’t around to measure it anymore so they had to settle for your average English peasant. Or possibly your average English aristocrat, who would have been better fed and probably taller, with a longer stride.

And here we’ll abandon boldface type so I can rearrange my sentences a bit.

In 1500 (or thereabouts, since we’re using imprescise measures), the old London mile measured eight furlongs, or 5,000 feet. How big was a foot just then? Funny you should ask. They were using the Germanic foot, which was bigger than the foot England adopted a little later, under Elizabeth, which meant the mile changed to 5,280 feet.

I don’t know what went into the decision to change it. Maybe Liz had small feet.

The Irish mile was 6,720 feet and the Scottish mile was 5,952 feet.

Meanwhile, Cornwall was working with a whole different set of measurements. The mile was 16,694.32194 feet, or a bit over three of I’m not sure who else’s miles–probably the ones we use today. The Cornish bushel was three Winchester bushels, or 18 gallons, and used for barley, wheat, and potatoes.

The what bushel? The Winchester bushel was a royal standard, named after the capital of tenth-century England, where Edgar the Peaceable kept a royal bushel to measure other bushels against. It sounds like something out of a fairy tale: If your bushel was too small, you’d have to find your way out of a subterranean labyrinth with only a potato to guide you –and the potato hadn’t made it to England from the Americas yet.

Edgar is also notable for having divorced an Elfleda to marry an Elfrida.

Winchester is not in Cornwall and Cornwall was an independent country in Edgar’s time. The Winchester bushel is just a point of reference–a rare standard measurement in an unstandardized time.

The Cornish apple gallon was seven pounds, although a plain old gallon was ten pounds. The Cornish pound was eighteen ounces but that seems to have applied only if you were measuring butter.

The warp was four fish. The burn was twenty-one fish. The mease was five hundred and five herrings. A knight’s fee was four Cornish acres.

Let’s cross the Tamar–that’s the river that forms Cornwall’s border–before we get too dizzy to find our way.

In 1215, the Magna Carta called for standard measurements with the desperate-sounding phrase “let there be one measure.” It wasn’t one of its more effective clauses. No one was around to enforce it, and over the years various gestures were made in the direction of standardization. Let’s review a random few of them:

In the sixteenth century, the rod was defined as the length of the left feet of sixteen men lined up heel to toe as they emerged from church. That was easiest to measure on a Sunday unless you wanted to assemble and choreograph the crowd yourself.

No, I don’t know why it had to be the left feet. Or leaving a church. Do feet change size during church services? 

That was–I suppose we should have guessed this–meant as a way to memorize the length of the rod, not as a standard for it. I probably shouldn’t include it as a gesture toward standardization, but it’s too good to leave out.

In 1668, John Wilkins, a founder of the Royal Society, was still calling for standardized measurements and added that units should increase by a factor of ten and create some simple relationship between length and volume. He was accused of being a spy for the European Union and since it didn’t exist yet he was banished into the far future, where he went on to lead a pro-metric organization.

In 1707, England celebrated its union with Scotland by imposing the English measuring system on Scotland. If Scotland didn’t vote, then and there, to join the European Union, the Euro, and the metric system, it was only because none of them had been created yet. It’s one of those lost opportunities that history’s so full of.

But enough. Let’s talk about Imperial measures.

The British Imperial System was created by a law passed in 1824 and again in 1878, which may speak to the effectiveness of the first one. Anything before 1824 was an English unit, and anything after was an Imperial unit. The Imperial gallon now held the same amount whether it was full of wine, ale, wheat, or dog sick. The yard and the pound were standardized. The rod and the chaldron (you measured coal with that) were abolished. So was lining up heel to toe after church.

The system was eminently sensible: A pound weighed a pound. A stone weighed fourteen pounds. A hundredweight weighed a hundred and twelve pounds–and still does. Please don’t ask me to explain that.

The U.S., just to be difficult, adopted most of the same measurements but gave them different values, ensuring that no conversation would be understood the same way if the participants came from opposite sides of the Atlantic. This leaves us with not just a ton but a short ton and a long ton, a short hundredweight (which, unfathomably, weighs a hundred pound) and a long hundredweight.

But we’re not done with the Imperial System: It kept the troy pound (240 pennyweight) and the avoirdupois pound (16 ounces or 7,000 grains). And of course, apothecaries’ weights.

The troy pound is used for precious metals and jewels. Apothecaries’ weights are a version of troy weights but not quite the same. Because why should you have one pound when you can have three?

I could go on–grains, drams, scruples, gills, minims–but let’s stop.

The point is that any fool can memorize this between the morning’s first sip of tea and the second one, before the caffeine has even had time to kick in. It’s simple: You have 16 ounces to the pound, 16 drams to the ounce, and 27.344 grains to the dram.

Of course, that’s only for the avoirdupois pound. Troy pounds have 12 ounces to the pound, 20 pennyweight to the ounce, and 24 grains to the pennyweight.

We’ll leave apothecaries’ pounds alone. That’s where you get into scruples. I have a few of those left, but like all apothecaries’ measurements they’re very small.

Skip forward, then, to the twentieth century, when the metric system was sneaking into Britain by way of scientists and businesspeople. One group liked to have measurement-related conversations with colleagues from countries that already used the metric system and the other group exported to those countries. Both thought it’d be simpler if they could use a system any fool could understand. Assorted committees and politicians talked about introducing the metric system but then looked down the barrel of history, heritage, and the tabloid newspapers and lost their nerve.

Until 1965, when the government announced a ten-year program during which the country would shift over voluntarily. Goals were set. Measures were recalibrated. Change was encouraged. Eventually, Britain would shift to the metric system and everyone would be happy.

This wasn’t simple. You had hard metrication, where the size of standard objects changed. You had soft metrication, where the object stayed the same but was measured in a new language. And you had viagra metrication, where the user needed a bit of help to toggle between soft and hard metrication.

Service stations changed over more or less by accident. Petrol (or gas, if you speak American) pumps were built to switch between liters and gallons so they could continue working in gallons for the time being, but that only worked when the price was under £1.999 per gallon. Above that level, they spoke metric and only metric. So when the oil prices went up, the industry threw its hands in the air and asked to be switched over so they wouldn’t have to pay for new pumps.

Many things changed and some didn’t, and no one could have predicted which would fall on which side of the divide: Road distances and speeds are still measured in miles and yards. Land is measured in acres. In pubs, cider and beer on tap (or draught if you speak British) are still sold in imperial units, but wine, whiskey, rum, and all their friends and relations are sold in metric units. Which makes perfect sense to a country that invented the gill, the scruple, and the minim. 

And even though Britain still sells petrol (or gas) by the liter, it measures fuel efficiency in miles per gallon. 

British politics and trade became more deeply integrated into Europe and a deadline was set for Britain to go metric. But by 1979, metrication had stalled. Polls were taken and people didn’t seem happy. Britain asked for a later date for the shift to the metric system. Then it asked for a later date than that.

Mirror, mirror, on the wall, who was the not-happiest of all? Why, the retail industry was the not-happiest of all, and eventually the postponements came to an end. That’s when a group of market traders got themselves arrested for boycotting the metric system. They weighed their produce on scales that used only the Imperial System and posted their prices only in pounds and ounces. When they were arrested, they called themselves the Metric Martyrs, and they were convicted and lost their appeals all the way to the House of Lords (which didn’t want to hear about it) and the European Court of Human Rights, which didn’t think using the Imperial System was a human right.

The original court case considered precedent all the way back to the Magna Carta, so let’s dredge up the full quote from the M.C. instead of the shortened form I quoted earlier. In true micro-managing form, it said, “Let there be one measure for wine throughout our kingdom, and one measure for ale, and one measure for corn, namely ‘the London quarter’; and one width for cloths whether dyed, russet or halberget, namely two ells within the selvedges. Let it be the same with weights as with measures.”

An ell is a measure used only for cloth. Russet in this context isn’t a color, it’s a kind of cloth–one common people wore. No one knows quite what halberget is, which seems appropriate. Listing the various kinds of cloth gives me the impression that they not only didn’t measure distance the same way they measured cloth, they didn’t measure any two kinds of cloth the same way.

The defeat of the Metric Martyrs brought Britain fully into its current  ideal and semi-metric chaos.