The Cato Street Conspiracy was a plot to assassinate the entire British cabinet on the evening of the 23rd February 1820, an act that the conspirators believed would precipitate the revolutionary overthrow of the established order.

The Background

Many of the ideas unleashed by the French Revolution of 1789 found support across the channel in Great Britain. One of the leading English Jacobins was a man by the name of Thomas Spence, famous for his dictum that "if all the land in Britain was shared out equally, there would be enough to give every man, woman and child seven acres each". After his death in 1814 a number of his followers formed the Society of Spencean Philanthropists which met at various public houses in London to discuss how the Spencean utopia might be brought about.

On the 2nd December 1816 these Spenceans organised a mass meeting at the Spa Fields in Islington which resulted in the Spa Fields Riot which may or may not have been a serious attempt to ferment a revolutionary coup. In the aftermath of the riot, four of the leading Spenceans, James Watson, Arthur Thistlewood, Thomas Preston and John Hopper were arrested and charged with high treason. All four were however acquitted, as the jury was unimpressed by the evidence of the main witness and government spy, John Castle whom they regarded as an agent provocateur. If anything, this experience seems to have made Arthur Thistlewood, who now emerged as the leader of the more radical Spenceans, even more convinced of the necessity of violent revolution.

On the 16th August 1819 another large scale public meeting was called at St. Peter's Field in Manchester, became known as the Peterloo massacreafter the attempt by the Cheshire Yeomanry to clear the assembled crowd resulted in eleven deaths. Peterloo seems to have convinced Arthur Thistlewood and his immediate followers that the tactic of holding mass public meetings was ineffective and so they conceived the alternative plan of killing the entire Cabinet; as Arthur Thistlewood said "High Treason was committed against the people at Manchester. I resolved that the lives of the instigators of massacre should atone for the souls of murdered innocents."

The Spenceans originally planned to carry out this mass assassination in December 1819 at the house of the Earl of Westmorland, but nothing came of it. However the plan was later resurrected when one George Edwards drew Thistlewood's attention to an item in the 'Fashionable Mirror' column in the The New Times of the 22nd February 1820 which referred to a cabinet meeting to he held on the following day at No 39 Grosvenor Square.

The plan was to gain admittance to the house at Grosvenor Square and decapitate the entire cabinet. 1 (Particular attention was to be paid to the severed heads of the Viscounts Castlereagh and Sidmouth2, who as favourite hate-figures of the radicals, were to be paraded through the streets on pikes.) After dealing with the cabinet the conspirators intended to seize control of the Tower of London and the Bank of England and declare a provisional government at the Mansion House. Thistlewood set about drafting a suitable proclamation to be issued after the coup, which proclaimed in lofty tones; "Your tyrants are destroyed - the friends of liberty are called upon to come forward - the Provisional Government is now sitting." It is also known that Thistlewood approached John Cam Hobhouse, the radical MP for Westminster, who agreed to head the proposed government.

Whilst Thistlewood went away to recruit sufficient men willing to join in with this plan for revolution, a John Harrison rented a small stable and hayloft at Cato Street, only a short distance from Grosvenor Square, which provided a convenient place for the conspirators to gather before the assault on Grosvenor Square.

The Conspiracy Betrayed

Unfortunately for the Cato Street Conspirators the whole thing was a set up. There was no planned Cabinet meeting at Grosvenor Street and George Edwards was in fact a government agent and had himself organised the placing of the item in The New Times. Thus the government was fully aware of the plot and appointed a Bow Street magistrate by the name of Richard Birnie to apprehend the conspirators. Birnie was given a battalion of the Coldstream Guards as well as police officers from Bow Street to arrest the Cato Street Conspirators.

A police officer named George Ruthven3 was placed in charge of the operation and took up a position in the Horse and Groom, a public house that overlooked the stable in Cato Street, and keep watch on the evening of the 23rd. As it happens the Coldstream Guards were late in arriving and George Ruthven decided not to wait for them and raid the Cato Street premises with the men he had available. They quickly overcame James Ings, who had been place on guard by the conspirators, and rushed the hay loft where Ruthven shouted, "We are peace officers. Lay down your arms." Some of the conspirators duly complied, but other did not and made a fight of it. During the resulting scrap one of the police officers, named Richard Smithers, was run through with a sword by Arthur Thistlewood, and collapsed bleeding to the floor and died soon afterwards. In the resulting confusion four of the conspirators, including Thistlewood, John Brunt, Robert Adams and John Harrison escaped out of a back window.

A reward of £1,000 was immediately offered for the Thistlewood, and the next morning he was captured at a friend's house at No. 8 White Street, Little Moorfields. The other three escapees were similarly captured within a day or two.

The fate of the Cato Street Conspirators

Since the authorities had failed to secure convictions after the Spa Fields Riot they were understandably nervous about allowing their agent George Edwards to testify. He was therefore packed off to Guernsey and was never called to give evidence. The case against the accused was largely based on the testimony of two of the conspirators named Robert Adams and John Hall who agreed to turn king's evidence in return for a pardon. The defence did its best to make the most the non-appearance of George Edwards before the court, nevertheless the jury returned a verdict of guilty against ten conspirators on a charge of high treason, all of whom were sentenced to death on 28th April 1820.

Not everyone was convinced that justice had been done. As The Examiner of the 30th April 1820 complained; "The machinery is too apparent: the revolting means taken to aggravate the plot, -the hypocrisy – the lying – the cold-blooded entrapping of human beings". But this made little difference to the outcome. Five of the men, Arthur Thistlewood, William Davidson, James Ings, Richard Tidd, and John Brunt were duly hanged at Newgate Gaol on the 1st May 1820, whilst another five, John Harrison, James Wilson, Richard Bradburn, John Strange and Charles Copper had their sentence commuted to one of transportation for life. John Cam Hobhouse who of course, had been party to the conspiracy but was never charged, observed the executions and recorded in his diary that "The men died like heroes. Ings, perhaps, was too obstreperous in singing 'Death or Liberty', and Thistlewood said, 'Be quiet, Ings; we can die without all this noise.'"

The stable at Cato Street enjoyed a brief fame as a tourist attraction. As The Sunday Observer of the 3rd March 1820 reported "The premises in Cato Street ... was visited by several thousand persons" and noted that the "blood of poor Smithers was still visible on the floor, and seemed to be avoided with a sort of reverential awe."

You will look in vain for a Cato Street in today's London, it was renamed Homer Street shortly afterwards.


1 It is worth noting that at this time Cabinet meetings took place in the evening over dinner at the home of one of the Cabinet members. No 39 Grosvenor Square was the home of the Lord President of the Council, Dudley Ryder, 1st Earl of Harrowby.
2 The Viscount Castlereagh was Robert Stewart, 2nd Marquess of Londonderry and Sidmouth was Henry Addington, 1st Viscount Sidmouth.
3 George Ruthven was a police officer and former spy who knew most of the Spenceans by sight


  • Edward Royle and James Walvin, English Radicals and Reformers 1760-1848 (Harvester Press, 1982)
  • Paul Johnson The Birth of the Modern (Phoenix, 1996)
  • The Cato Street Conspiracy - The trial that shouldn't have been?
  • Peter Cunningham, Hand-Book of London, 1850
  • The Cato Street Conspiracy