The gunpowder plotter Guy Fawkes being arrested while trying to blow up the Houses of Parliament.
More than six centuries after Edward III first enshrined the crime of treason in English law, the letter that thwarted one of the most infamous acts in the nation’s history is to go on public display.
The anonymous Monteagle Letter, of 26 October 1605, warned the peer Lord Monteagle not to attend the opening of parliament on 5 November, “for they shall recyeve a terrible blowe this parleament and yet they shall not seie who hurts them”.
Parliament did not blow; the tipoff led to the discovery of Guy Fawkes with 36 barrels of gunpowder hidden in a storeroom in the palace of Westminster.
The original letter will be on public show, for the first time it is believed, alongside other documents relating to the audacious plot and its aftermath as part of a free exhibition at the National Archives in Kew, London, which also includes documents from other moments that shaped the nation’s history.
One of Guy Fawkes’ seven confessions, thought to have been extracted after torture, and the sanctioning by King James I of torture citing: “the gentler Tortures are to be first used unto him et sic per gradus ad ima tenditur [and so by degrees proceeding to the worst]”, are displayed.
An original copy of the 1606 Thanksgiving Act, after Londoners were encouraged to celebrate the king’s escape with his life by lighting bonfires, and which decreed that 5 November – Bonfire Night – be celebrated annually, is also displayed. It remained law until 1859.
The Bag of Secrets: A History of the Gunpowder Plot Papers
The Gunpowder Plot papers were kept until the 19th century in the Bag of Secrets, a leather bag kept under lock and key, containing some of the most important treason documents of the land, which is also on display.
Dr Daniel Gosling, a legal records specialist, said: “It was the biggest treason attempt in British history, on a scale that hasn’t been seen before.
This one, if successful, would have killed the king, his closest family, all of his counsel, members of parliament. So it would destroy not only the royal family but the government, and the physical building of government.”
The exhibition Treason: People, Power and Plots, opening, appropriately, on 5 November and running until 6 April 2023, begins with the Treason Act of 1352, though lawyers use 1351 as the date of the act, with historians using 1352 because of the medieval calendar.
The original ornate parchment and ink statue roll in Anglo-Norman French that contains the act – and is shown for the first time – is at its heart.
It includes the clause of attempting to kill or imagine the death of the monarch or eldest heir to the throne, or levy war against the monarch – elements that remain today.
The law was constantly added to.
In 1441 Eleanor Cobham, the Duchess of Gloucester, known as the “royal witch”, was found guilty of astrology, magic and necromancy – now also categorised as treason – having been accused of summoning demons to predict when Henry VI would die.
One parchment roll, issued by Henry VII, is the 1485 attainder of Richard III for treason – even though Richard had already been killed at the Battle of Bosworth.
Henry VII, who had undoubtedly himself committed treason, backdated his reign by one day to allow him to charge his now dead rival with treason instead.
The detailed charges against Anne Boleyn, accused of incest with her brother and of treason for plotting the death of Henry VIII, are included.
Rarely seen in public, they were also kept in the Bag of Secrets.
It was under Henry VIII’s reign that the Treason Act also came to include poisoning.
Richard Roose, cook to the Bishop of Rochester, who poisoned the porridge he served (the bishop did not eat it but others did) was convicted of treason against his master, and boiled alive at London’s Smithfield market.
Poison was removed from the act after Henry VIII’s death.
In a spectacular reversal of the treason laws, the trial documents relating to Charles I’s conviction and execution for treason, show treason defined as against the people, rather than the monarch.
This reverted on the accession of Charles II.
The charge of treason was “warped, adapted and expanded” over the centuries, said Dr Euan Rogers, principal medieval specialist.
“But the core of the 1352 act remains today.”