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The Cato Street Conspiracy

23 February 1820: Bow Street Runners arrest the conspirators | Alamy

Thomas Ardill and Chris Day

7 min read

Ahead of the anniversary of a historic conspiracy, curators Thomas Ardill and Chris Day recount the dramatic tale of how a government spy infiltrated a plot to murder the cabinet and spark a revolution

Just before 8.30 on the morning of the 1 May 1820, five men – Arthur Thistlewood, William Davidson, James Ings, Richard Tidd and John Brunt – gathered behind the Debtor’s Door of Newgate Prison, London. They were waiting to take their last walk: to the gallows, and to a traitor’s death.

The men were parliamentary reformers; would-be revolutionaries: advocates for universal male suffrage at a time when only about four per cent of the British population could vote. A crowd of thousands awaited them. Fearing rescue attempts, the government had posted troops around the prison. A fearsome-looking axe was specially commissioned for the occasion, but it was a stage prop. Laid in front of the platform, it symbolised the state’s readiness to cut down the tree of liberty wherever it took root. The men were hanged and, after they were dead, beheaded by a masked man wielding a surgeon’s knife. Their heads were held aloft and their names proclaimed as traitors.

Thistlewood, Davidson and the rest had been convicted of treason for their part in the Cato Street Conspiracy of 1820. Their crimes, discovery and deaths are now told by documents and objects at two landmark exhibitions at The National Archives and the Museum of London Docklands.

The years that followed the end of the Napoleonic wars in 1815 were a time of acute economic distress. Riots were commonplace, but in government the real fear was of radical reformers taking advantage of this widespread discontent to further their political objectives.

In 1817 the home secretary, Lord Sidmouth, called reformers a “malignant spirit …[with] parliamentary reform in their mouths, but rebellion and revolution in their hearts”. He persuaded Parliament to suspend habeas corpus, and make permanent a 1795 Treason Act, which updated the original 14th century law to make clear that attempts – violent or peaceful – to subvert Parliament were treasonous.

Thistlewood was soon charged under this Treason Act for his role in the Spa Fields riots of December 1816. A public meeting calling for reform had become a riot, with rebels even attacking the Tower of London. The government claimed it was intended to be the first action of a revolution, but the trial collapsed when its star witness was revealed to be a spy and provocateur. 

In August 1819, cavalry were sent against a peaceful meeting of reformers in St Peter’s Field, Manchester. The Peterloo Massacre left 18 dead and many more seriously injured. Arrests and a ban on public meetings followed, but a clandestine world of secret societies and conspiracies remained, as did Sidmouth’s network of spies.

In the summer of 1819 Thistlewood had just been released from prison, where he had served a sentence for challenging Sidmouth to a duel. He began attempting to foment revolution with his group, the Spencean Society of Philanthropists. They had a new member of great revolutionary fervour, George Edwards, who became one of Thistlewood’s closest confidantes. He was also a spy, working for the Bow Street Runners (the first professional police force).

Thistlewood killed one of the Runners, stabbing him through the heart

His reports, closely written on thin strips of paper and signed under his codename, “W---r”, are now held at The National Archives. By early 1820, possibly under Edwards’s suggestion, the Spenceans had decided at one of their regular dinners that they would assassinate the entire cabinet. But parliamentary recess and mourning for the late George III meant that there had not been one for some time. The Spenceans had a stockpile of weapons but were running out of money and squabbling. They were on the verge of giving up their plan.

Then, on 22 February, Edwards arrived at their meeting with a copy of the obscure New Times newspaper, carrying a notice of a cabinet dinner the next night. Thistlewood ordered them to action. They would meet in a stable loft on Cato Street, off the Edgware Road, the following night. They would then go to the home of Lord Harrowby, the lord president of the council, gain entry and murder the ministers on the command of: “Citizens – do your duty!”

The dinner was a fiction. The notice had been placed by the government to entrap the men. As they prepared at Cato Street, Bow Street Runners arrived and arrested Davidson, on guard at the stables, before ascending to the loft. There, Thistlewood killed Richard Smithers, one of the Runners, stabbing him through the heart. Gunshots flared, candles were snuffed. While some men were arrested, Thistlewood and others escaped, but were soon rounded up and 13 were charged with high treason. The trials began at the Old Bailey on 17 April with Thistlewood the first defendant.

Treason is about intent. It is the “compassing and imagining” of something threatening to the integrity of the Crown which raises criminal acts (both “overt”, such as violence and rioting, and treacherous speeches or writing) from lesser crimes to the highest one. Thistlewood argued that he had no treasonous intent. Conspiring to kill ministers is a crime, but it is not treason unless it was intended to bring about a revolution and threaten the Crown and constitution. Thistlewood’s barrister, John Adolphus, argued that the evidence of revolutionary intent provided by informers and co-conspirators was unreliable because of their questionable characters. The idea that the Spenceans, less than 30 in number, genuinely conceived that they might overthrow the government was fanciful, Adolphus argued. The jury disagreed. All the accused were found guilty. On 28 April Thistlewood, Tidd, Ings, Davidson and Brunt were sentenced to death. The others were transported to Australia for life, one was imprisoned. 

The condemned men were given a chance to plead for mercy, during which Thistlewood attacked the “ever at invention” Edwards, who never had money to buy a pint but always had cash for arms, for entrapping him. He was nonetheless unrepentant, stating that “the assassination of a tyrant has always been deemed a meritorious action”.

The men spent only a few days in Newgate Prison. They remained principled and defiant. They refused the ministrations of the prison’s Anglican chaplain and the supposed solace of his “condemned sermon”. James Ings even joked that “he wished that his body might be conveyed to the King, and that his majesty, or his cooks, might make turtle-soup of it!” But there was no laughter when their families visited to say their farewells.

Once the men’s heads were off, they were put in coffins with their bodies. Quicklime was poured over them to speed up the process of decomposition and they were buried beneath the passage to the Newgate cells. Their families petitioned for the return of their bodies; Arthur Thistlewood’s widow, Susan, begging the King for his “cold and mangled remains” so she might perform “the last mournful duties”. She received no reply.

Supporters of the Spenceans also attempted to have George Edwards charged with treason, claiming that he was the chief instigator. They presented a request for his arrest to Matthew Wood MP, the radical City of London politician and magistrate. Wood attempted to meet Sidmouth to discuss the allegations but could not, so raised them in the Commons on 2 May 1820, proposing that the House resolved to examine Edwards. He was persuaded that the House was no place for a high treason trial. Edwards was eventually sent to South Africa, his usefulness spent. The government never admitted its part in the conspiracy but the records at The National Archives prove it. As cabinet minister George Canning remarked to Wood, all governments, from time-to-time, had to “defeat by the prostitution of wicked men, the plots of men as wicked”.

Thomas Ardill is a Curator (Paintings, Prints and Drawings) at the Museum of London; Chris Day is Head of Modern British Records at The National Archives

Treason: People, Power and Plot is at The National Archives until 6 April; Executions is at the Museum of London Docklands until 16 April 

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