Feb. 23, 2023

The Cato Street Conspiracy

The Cato Street Conspiracy

February 23, 1820. An agent provocateur helps British police foil a plot to assassinate the Prime Minister and his entire cabinet.


Cold Open

It’s the afternoon of December 2nd, 1816 in London, England, and a riot is in progress.

A mob rampages through the streets, breaking windows and robbing any well-dressed gentleman who crosses its path. Leading the charge is 42-year-old revolutionary Arthur Thistlewood.

Earlier today, Arthur spoke at a radical political meeting where he whipped into a frenzy 10,000 working-class Londoners over their lack of voting rights. He declared his intention to riot and invited the crowd to join him. Now, Arthur watches as those who did cause chaos on the streets of London.

Eager to participate in the action, Arthur checks his pockets and discovers he only has a few of spare musket balls left. So he raises his leg… and kicks open the door of a nearby gunsmith’s shop. He pushes his way inside and points his pistol at the shocked storekeeper, ordering him to stay still.

As Arthur stuffs his pockets with bullets, the storekeeper reaches behind the counter and pulls out his own gun… but Arthur notices him move, aims, and fires. The gunsmith slumps to the floor. But a flicker of movement catches Arthur's attention. He swings round, gun still raised — but it’s only rioters running past the shop windows — though in the wrong direction.

Confused by their hasty flight, Arthur leaves the gunsmith's shop and steps back outside. Gunfire erupts from one end of the street and Arthur turns his head to see armed soldiers from the Tower of London. He shouts at the rioters to stand their ground, but they continue to turn and run. Within seconds, the street is fully deserted, leaving Arthur standing alone as soldiers order him to drop his weapon and put his hands in the air.

In the wake of the Spa Field Riot, as this uprising will come to be known, Arthur will be arrested as a ringleader. In the resulting trial, the prosecution's chief witness will be a government spy who had infiltrated the revolutionary’s circle. But given his murky occupation, the evidence he submits against the rioters will be deemed unreliable. Much of the jury will conclude that it's likely the spy was employed to incite the riot and will therefore find no reason to convict the revolutionaries for treason.

Arthur’s lucky acquittal will leave him free to engage in more political agitation, and his grievances against the British establishment will only escalate. Three years after the Spa Fields Riot, Arthur will scheme again, this time to assassinate the British Prime Minister and his cabinet, but another spy will foil the plot. This time the espionage will not work in his favor, and Arthur will face the full wrath of the law after the Cato Street Conspiracy collapses on February 23rd, 1820.


From Noiser and Airship, I’m Lindsay Graham and this is History Daily.

History is made every day. On this podcast—every day—we tell the true stories of the people and events that shaped our world.

Today is February 23rd, 1820: The Cato Street Conspiracy.

Act One

It’s January 29th, 1820 in London, more than three years after the Spa Fields Riot.

Arthur Thistlewood leans forward and eyeballs the men seated at a table around him. Not a single one wavers as Arthur explains his plan to assassinate the Prime Minister and his cabinet.

Since taking part in the Spa Fields Riot, Arthur’s desire for radical political reform has only become more radical. As it stands now, just 2 percent of the British population can vote in political elections, and the government is unwilling to consider any expansion of the franchise. Instead, they have remained openly hostile toward any calls for greater voter participation.

Last year, 15 people were killed when cavalry charged a crowd of working-class men, women, and children gathered in Manchester for a rally demanding the vote. Rather than accept any wrongdoing for the massacre, the government passed a series of laws known as the Six Acts suppressing similar political rallies. Arthur has decided to fight back. He wants to enact change through violent means, and in three days’ time, he expects his plan to come to fruition.

Arthur tells his fellow plotters that they will meet here, in their secret loft above the stables on Cato Street. Then, they will proceed to a townhouse in Grosvenor Square owned by Lord Harrowby, a member of the Prime Minister Lord Liverpool’s Tory government. There, they will murder the entire cabinet while the politicians are at dinner. And with the Prime Minister dead, Arthur will set up a committee to purge the old regime and form a new government that serves the people, and not just the rich.

Arthur pauses, waiting for the men in the room to give their assent. But no one speaks as they all listen to a slow and monotonous church bell ringing constantly and ominously in the distance. The conspirators exchange questioning glances. The church bells should not be ringing and when they do like this, its usually in alarm. Then the men hear footsteps approaching, and Arthur wonders if the plot has been discovered. The footsteps grow nearer but instead of the authorities, it's the surprise arrival of another conspirators with an alarming message: King George III is dead.

Arthur is crestfallen. He has no love for the monarch and his riches when ordinary Englishmen cannot afford to eat, but the king's death does pose an inconvenient complication. The government will now go into mourning which means the dinner at Lord Harrowby’s house will be canceled. With their plan foiled, Arthur assures the conspirators that they will try again—but he is not aware that one of the men in the loft will soon report every incriminating word to the highest levels of the British government.

Two days after the king’s passing, this turncoat accomplice, George Edwards, is shown into the office of Lord Sidmouth, the Home Secretary. As an undercover agent, George is here to report the Cato Street Conspiracy to one of the men who would have been killed if the plot were successful.

Sidmouth is pleased with George’s work, but he can’t help regretting that the king’s death has robbed them of the chance to catch the conspirators red-handed. He was excited to see the outcry that would follow the dramatic, last-minute reveal of the murderous plot, confident that the government could use the resulting turmoil to pass even more draconian laws and eliminate these radicals and their demands forever. But now, they have to find a new plan.

George clears his throat and suggests an idea: Lord Harrowby must host a new dinner when the period of mourning is over — in say, three weeks. If it’s mentioned in the society pages of London’s newspapers, George can show it to Arthur and convince him to resume the plot then. The conspirators can be apprehended on the day of the attack.

Sidmouth claps his hands with glee and then says he has an idea to make the plan even better. To prevent any chances of a successful assassination, the Prime Minister and cabinet do not even need to be at Lord Harrowby’s — the plotters only need to think that they are. With a grin, Sidmouth picks up a pen and paper, ready to plant a story in the London Times, and set the plot in motion.

Back on Cato Street, George will feed Arthur the story about the rearranged cabinet dinner, and the Cato Street Conspiracy will be resurrected. In the coming weeks, George will transform from a mere spy to an agent provocateur, encouraging and aiding the plotters in their illegal endeavor. But he will need to avoid arousing the plotters’ suspicions for another three tense weeks before he can than snear them in his trap.

Act Two

It’s February 22nd, 1820, one day before the Cato Street Conspiracy will collapse.

39-year-old William Davidson knocks at a townhouse in Grosvenor Square. His face lights up as one of Lord Harrowby’s servants opens the door and welcomes him in. William, a skilled cabinetmaker, has fallen on hard times and has been forced to take on menial repair jobs, including at Lord Harrowby’s house. But William is hiding a secret. He isn’t just a  handy man — he’s one of the Cato Street Conspirators.

A week ago, ringleader Arthur Thistlewood summoned his followers to deliver good news — the plot was back on. He presented them with a copy of The Times and pointed to a story in the papers, saying the Prime Minister and his cabinet would hold a dinner meeting at Lord Harrowby’s the following week. A delighted Arthur said there was no need to change any part of their old plan — they could proceed exactly as they intended a month ago. So now, William is here at Lord Harrowby's house to survey the scene of the upcoming assassination attempt.

As he enters the house, William tries to commit its layout to memory. The servant leads him to the kitchen, where she thrusts a cup of tea into William’s hands. He politely thanks her and asks whether Lord Harrowby has any more repair jobs that need his attention. The servant shakes her head. Nothing needs to be fixed, nor is Lord Harrowby even home — he’s visiting his estate at Burnt Norton in Gloucestershire.

This puts a frown on William's face. Burnt Norton is 100 miles from London. He doesn’t understand how Lord Harrowby will make it back in time for the dinner. William tries to act casual when he asks when Lord Harrowby will return for his dinner with the Prime Minister. But the servant doesn’t know anything about any dinner, and certainly not one with the Prime Minister. William doesn't know what to make of the servant’s revelation, but he knows he needs to report it to Arthur as soon as he can.

Later that day, the conspirators assemble at their Cato Street hideout. William pulls Arthur to one side and explains there is no dinner at Lord Harrowby’s house tomorrow night. Arthur is confused. But police informant George Edwards overhears and appears at Arthur’s shoulder, reassuring them that the servant must be mistaken. After all, the dinner is announced in the newspaper. William shakes his head, unconvinced feeling that George is acting shifty.

But throughout the rest of the night's planning George manages to avoid arousing any further suspicion. The following evening, he’s able to slip away from his other conspirators and secretly rendezvous with a local magistrate. He reports that the conspirators are arming themselves in the Cato Street loft and they’ll be setting off for Lord Harrowby’s house in Grosvenor Square in the next few minutes.

The magistrate nods but takes no action. George repeats himself, trying to convey the urgency of the situation. But the magistrates brushes him off, explaining that he needs more soldiers to arrive before he can arrest the conspirators. All he has now are 12 men from the Bow Street Runners, the name of the police force in this part of London.

George looks over at these officers, lounging around him. He’s horrified by their nonchalance. Again, he declares that the plot is about to begin. Even if the Prime Minister is nowhere near Grosvenor Square, the servants have not been cleared from Lord Harrowby’s house — and nobody knows what Arthur’s armed band will do when they realize their plot has been foiled. George continues to plead with the magistrate to raid the loft now before the conspirators leave. The magistrate hesitates, then finally agrees.

George picks up a sword and joins the Bow Street Runners as they crowd into the street. Though they will be outnumbered by the Cato Street Conspirators, the element of surprise will work in their favor. The plotters will be defeated and Arthur’s plan to assassinate the Prime Minister and overthrow the government will soon be foiled.

Act Three

It’s 7:30 PM on February 23rd, 1820 at the conspirators’ base in Cato Street, minutes after George Edwards informed a magistrate that the plot is about to begin.

Inside the busy loft, the conspirators ready themselves for the attack on Lord Harrowby’s house. Arthur Thistlewood picks up a flintlock pistol from a tableful of weapons and tests its weight in his hands. But before he has a chance to prime the gun with powder, a man rushes through the doorway wearing a blue greatcoat and top hat.

Arthur’s heart sinks at the sight of the Bow Street Runners' uniform. As he reels from the surprise, he receives another shock. Behind the onslaught of officers is George Edwards, with a sword in hand.

Arthur glares at the traitor and reaches for his own blade. A police officers commands him to lay down his arms but Arthur refuses. He’s already been betrayed. He has no intention of being arrested too.

One of the officers raises his pistol and orders Arthur to lower his sword. But Arthur refuses, stepping forward quickly plunging the blade into the officer's chest.

Before the other Bow Street Runners can react, Arthur breaks the room’s lantern, plunging the loft into darkness. From a corner, he listens to the sound of a scuffle, punctuated by the occasional flash of a gun firing. Then, a silence descends on the room. One of the conspirators asks what’s happening. Another answer in a whisper that the Bow Street Runners have retreated.

Hearing this, Arthur creeps over to a window, where he stashed a rope ladder for emergencies. He eases the window open and climbs out, quietly dropping to the ground and dashing into the distance. But Arthur’s time on the run doesn't last long. The very next morning, he’s picked up by the Bow Street Runners after being discovered hiding in the house of an accomplice.

Just like with the Spa Fields Riot, Arthur will be arrested due to the actions of a police spy. Only this time, Arthur will receive no sympathy in court. Despite some reservations about the use of an agent provocateur, the judge and jury will declare Arthur guilty of treason earning Arthur a sentence of death and a public hanging for his role in the failed plot to assassinate the Prime Minister and his entire cabinet on February 23rd, 1820.


Next onHistory Daily. February 24th, 1917. The British present the Zimmermann Telegram to US President Woodrow Wilson, an intercepted message that reveals new threats against the United States and persuades the nation to enter World War I.

From Noiser and Airship, this is History Daily, hosted, edited, and executive produced by me, Lindsay Graham.

Audio editing by Mollie Baack.

Sound design by Derek Behrens. 

Music by Lindsay Graham.

This episode is written and researched by Scott Reeves.

Produced by Alexandra Currie-Buckner.

Executive Producers are Steven Walters for Airship, and Pascal Hughes for Noiser.