What shall we be doing in the summer of 2015? A general election is scheduled for 7 May. If Theresa May gets her way, we shall be voting on whether to denounce a list of rights and liberties that will have been binding on our rulers for little more than 60 years.

The following month, we shall be celebrating a list of rights and liberties that will have been binding on our rulers for 800 years. So it may not be easy to persuade voters that 2015 is a good year to scrap the human rights convention.

‘Does Magna Carta mean nothing to you?’ asked Tony Hancock in 1959. ‘Did she die in vain?’ The confusion encapsulated in those immortal lines from one of television’s best-loved comedians is widely shared today.

The ‘great charter’ was not the foundation of human rights or the origin of trial by jury and still less was it the origin of parliamentary democracy. Ten weeks after he had granted it to the barons, King John had Magna Carta annulled by the Pope. But John died the following year, leaving his nine-year-old son Henry III in urgent need of baronial support. So Henry’s regent swiftly revised and reissued Magna Carta in 1216 and then again in 1217. When Henry came of age in 1225, he issued a further revised text in his own name. It was this version – much shorter than the original – that was confirmed by Edward I in 1297 and found its way on to the first statute roll. Most of the 1297 statute was repealed during the 19th and 20th centuries, leaving only three sections in force today.

And it is unlikely that all the copies of Magna Carta were sealed on 15 June 1215, even though that is the date they bear. The king met the barons at Runnymede over a period of several days. Copies of the agreement they reached were written up by scribes immediately after the event and distributed a week or so later, in a process not unfamiliar to today’s lawyers.

Of those copies, four have survived. Two are in the British Library, one is owned by Lincoln Cathedral and one is in Salisbury Cathedral. In the eight centuries since they were written, they have never all been in the same place at the same time. But today the British Library and the two cathedrals are announcing that all four copies of Magna Carta will be brought together in the library for just three days in February 2015. The Monday will be reserved for media, distinguished guests and sponsors (the unification event is being sponsored by Linklaters). Tuesday will for the 1,215 children and adults who win a ballot for entry. And Wednesday will be for the curators and specialist historians who will have a once-in-800-years chance to study the manuscripts side by side in the library’s conservation centre.

As you would expect, the British Library will be mounting a further Magna Carta exhibition in the spring and summer of 2015, open to all. And there will be many other commemorative events, plans for which are already being discussed with reporters – including me.

Dr Claire Breay, lead curator of medieval manuscripts at the British Library, fizzes with excitement at the prospect of seeing all four copies of Magna Carta together. But why should that be? She has two copies to look at already. One was badly damaged by fire in 1731, but still has part of the great seal attached. The other has lost its wax seals over the centuries and strikes me as surprisingly small, with its Latin text tightly packed to fit the available parchment.

Breay tells me that this copy of Magna Carta is really rather large for an early 13th-century charter. Although it is hard to read in the low-light conditions required for public display, a magnifiable reproduction may be accessed from any computer. Why then is it so important to see the four originals together?

‘That’s what historians always want,’ she says; ‘to compare texts. There’s something about the materiality of them that you can’t get from a photograph. It’s an amazing, mind-blowing moment in history and it’s an amazing moment for the study of history.’

I find Breay’s excitement infectious. In essence, Magna Carta was a peace treaty. It established for the first time that the king was subject to law, not above it. And there is something rather romantic about a room full of scribes sitting down 800 years ago and copying out, in Latin, ‘We will sell to no man, we will not deny or defer to any man either justice or right’ — words that are still on the statute book today. Might they form the basis of legal action against the present lord chancellor?