Since 1889 a simple platinum iridium cylinder has been hidden away under no fewer than three glass bell jars and secured with three keys – two of which are in France – and placed inside a secure vault in the Parisian suburb of Sevres.

For this is no ordinary lump of metal… it even has its own name as befits its hallowed status. 

It’s not big at all, in fact it weighs just one kilogram. As a matter of fact it’s the only thing that weighs one kilogram in the entire universe. Sure there are some things that get close, give or take a zillionth of a nano thingy. 

But ‘Le Grand K’ is the literal definition of the kilogram. The original unit. The one by which all other are measured – it’s the Jimi Hendrix of weights. It’s the literal physical embodiment of an idea…  not a representation but the thing itself. Which explains all the glass domes I suppose.

It is so precious that it only emerges blinking into the daylight every 40 years, just so that the other replica ‘not quite so’ Grand Ks can be compared to it. 

It’s as close in scientific terms as it gets to being a piece of the true cross – and it’s a matter of fact that scientists actually make pilgrimages to it – not on their knees and whipping themselves with branches, they’re scientists after all, but quietly, possibly carrying clipboards and sporting lab coats I should imagine.

But in a small conference centre a few steps from the Palace of Versailles, an international meeting of people whose job it is to vote on things like kilograms decided to upset le cart aux pomme. 

On any other year, the annual meeting of the official weights and measures steering committee could be relied upon to respond to item 7 on the agenda ‘Shall we continue to keep Kilograms the same?’ with a short period of token beard stroking and biro tapping before agreeing ‘yes’ and then going out for a curry and a beer.

So what happened last month then?

Perhaps one of them laughed at the other’s leather elbow patches or poked fun at him missing a square root sign off a complex equation?

 We will probably never know, but we are all saddled with the Earth shattering consequences. Because a show of hands overturned the natural order of things – with the assembled delegates deciding to hand Le Grand K its P45. 

Now the kilogram will be defined by an abstract constant of nature – using the speed of light and factoring in Planck’s constant which you will recall, and I feel a bit silly even mentioning it, links the amount of energy a photon carries with the frequency of its electromagnetic wave. It’s a shame, whatever will they replace next? I’m a bit concerned that they might replace the genuine Keith Richards with the measurable concept of a legendary Stones frontman… please don’t let this happen.