Written in an exquisite hand on a sheet of parchment, about 15in tall and 20in wide, the Magna Carta has long been seen as the cornerstone of the freedoms we take for granted

Go into Salisbury Cathedral, turn right and head for the chapter house, and you will find the most extraordinary document not just in Britain, but perhaps in the world.

Written in an exquisite hand on a sheet of parchment, about 15in tall and 20in wide, it has long been seen as the cornerstone of the freedoms we take for granted.

Every day, visitors arrive from around the world to stare at one of the only four surviving original copies of King John’s Great Charter — or as it is better known, Magna Carta.

It was first signed on June 15, 1215, which means that this year marks its 800th anniversary.

And although much of this medieval Latin document now seems obscure, its role in our history cannot be exaggerated. Far more than any parliamentary law, it is the Magna Carta that has become the supreme symbol of liberty, justice and democracy.

For Lord Denning, perhaps the most eminent British judge of the 20th century, it was simply ‘the greatest constitutional document of all times — the foundation of the freedom of the individual against the arbitrary authority of the despot’.

Yet today, 800 years on, the freedoms it represents are under attack as never before.

The threat comes not from tyrannical kings or over-mighty barons, but from an unholy combination of authoritarian ministers, unaccountable lawyers and grasping technology corporations, who care nothing for our traditions of freedom and privacy.

Almost every day, it seems, brings new threats to our hard-won civil liberties.

For the past few days, the Mail has been reporting the shocking story of a Scottish grandmother who was dragged out of a Ken Dodd comedy show and jailed for three nights for the supposed crime of hugging her teenage granddaughter.

Though she has now been released on the orders of a judge, the secretive Court of Protection which had instructed her to break off contact with her own granddaughter wanted her locked up for three months.

Alas, such disturbing stories are so numerous that it would take a book to recount them all.

Take, for example, the revelation that under anti-terror laws, the security services have demanded some half a million copies of our digital communications in just 14 years.

Outrage

Despite the furore about phone-hacking at the News of the World, the really worrying threat is not from the free Press but from our own security establishment, which has hacked journalists’ phones to obtain information about their sources, and poked its nose into countless people’s private concerns.

In 2014, according to an investigation by the Spectator magazine, the police invoked anti-terror powers under the Regulation of Investigatory Powers Act to snoop on our private communications every 73 seconds.

The Mail has been reporting the shocking story of a Scottish grandmother who was dragged out of a Ken Dodd comedy show and jailed for three nights for the supposed crime of hugging her teenage granddaughter

These are figures that would shame a Communist dictatorship — let alone a country that prides itself on its tradition of liberty.

This relentless erosion of our freedoms is increasingly resented by the public. And as the story of the Magna Carta shows, the men who govern Britain are deluding themselves if they believe they can ignore the outrage of their subjects for ever.

The Great Charter was born out of a long, vicious struggle for supremacy between King John, the spiteful younger brother of Richard the Lionheart, and his barons, who resented the King’s habit of imposing crippling taxes to pay for his foreign wars.

After the rebellious barons marched on London, John met them at Runnymede in Surrey, and hammered out a deal — and the Magna Carta is its written confirmation.

In an age when kings were only too keen to make up the law as they went along, throwing their opponents behind bars and levying whopping new taxes whenever they felt like it, here was a document that explicitly limited the power of the monarch — or, in today’s terminology, the State.

In clause 38, for example, the Charter guarantees that ‘no free man shall be taken or imprisoned … except by the lawful judgment of his peers or by the law of the land’.

And the very next clause promises that ‘to no one will we sell, to no one will we refuse or delay, right or justice’ — a principle that in many parts of the world, such as Putin’s Russia, is too often ignored.

Shameful

King John died in October 1216, but the Magna Carta has endured. Indeed, as a statement of principle it is simply extraordinary.

And if you want to understand why Britain stands unrivalled as the cradle of liberty, then you need to start with the events of 1215.

The tragedy, though, is that the very principle of freedom is perhaps more embattled now than at any time in living memory.

Little by little, successive governments have been quietly eating away at our civil liberties. Take, for example, Tony Blair’s shameful plan to introduce compulsory ID cards, which was scrapped by the Coalition in 2010 — although only after Labour had already wasted a staggering £250 million on it.

Alas, it has never gone away. Only a few weeks ago, the Mail reported that the Government is planning to introduce ID cards by the back door in the form of the ‘Verify’ project, which will give every citizen a ‘virtual ID’ but could allow government websites to track and store your confidential data.

Meanwhile, the NHS is demanding more personal information for its databases, which could be used by insurance or pension companies to force some of us to pay higher premiums. And only last month the NHS announced plans for a bank of genetic data on all of us.

Even more shocking, successive governments have been itching to roll back the right to a jury trial, or, to use the Magna Carta’s words, the lawful judgment of your peers.

Under Labour, both Jack Straw and David Blunkett tried and failed to introduce trial by judge, not by jury, for less serious offences — supposedly to cut costs and speed up the court process.

Almost incredibly, the Coalition government has failed to learn the appropriate lesson. Indeed, after the London riots of 2011, one of the Government’s countless unelected ‘policy tsars’, Louise Casey, even insisted that we should drop the idea that the right to a jury trial is ‘sacrosanct’.

As for the security services’ addiction to snooping, it has had disastrous effects. For it is precisely the culture of unnecessary prying on guiltless citizens that has encouraged posturing and self-styled crusaders such as the former CIA employee Edward Snowden, whose wholesale leaks irresponsibly revealed how our intelligence agencies tracked the lethal activities of terrorists and crime lords.

Thus his recklessness has desperately endangered genuine and deadly serious life-or-death operations.

Yet perhaps the most insidious threat comes not from the state, but from the vast technology corporations on which we have become so dependent, such as Google — a company, incidentally, with extraordinary access to Downing Street. After all, just think about everything you have ever typed into that infernally useful search engine.

Cynical

As with other internet giants such as Facebook, Google’s surveillance of its users is remarkably sophisticated. And under pressure from consumer groups outraged at the invasion of their privacy, Google even insisted its email customers could have no ‘reasonable expectation’ that their messages would remain private.

Google’s surveillance of its users is remarkably sophisticated. And under pressure from consumer groups outraged at the invasion of their privacy, Google even insisted its email customers could have no ‘reasonable expectation’ that their messages would remain private

The irony, therefore, is that even as we are preparing to celebrate the document that has come to embody our basic freedoms, we seem wilfully blind to their cynical, remorseless erosion.

Last summer, David Cameron described the Great Charter of 1215 as ‘the foundation of all our laws and liberties’. He wanted, he said, to ‘use this anniversary as an opportunity for every child to learn about the Magna Carta, for towns to commemorate it, for events to celebrate it’.