So, in 1810 Britain had a decent political crisis in London when the House of Commons had some radicals thrown in Prison, a Radical MP Francis Burdett denounced this and got himself tagged with an arrest warrant by the house.
Burdett responded to the declaration by barricading himself in his home. The people of London responded by supporting him. Mobs filled the streets, barricades were made, the Tower of London had to flood its moat. All troops with-in 100 miles of London were ordered to arrive the city, and some more conservative voices in Parliament suggest that Arthur Wellesley should be recalled from Spain to take command. Some units clash with rioters and such, over all its very unpleasant.
And then steps in one of the greatest living War Hero's Britain has produced so far in this war. Thomas Cochrane who at the time, is also a radical MP. He takes a rather drastic action. He arrives at Burdett's house with a case of Gunpowder, and the intent to mine the house, in the event of a raid by the Police or the Army to take Burdett into custody. IRL he was talked down, and asked to leave, taking his Gunpowder with him. But the question is what if he hadn't?
Had the Mined house gone off as Police finally slipped in to take Burdett, there would have been many dead police, and the only viable reaction by the goverment would be to call it an act of terrorism or treason. Cochrane would be the obvious target, with the support of the Mobs on London's streets. He would have little choice but to take command, and try to lead a revolution of sorts in London. If London becomes the site of a re-enactment of Paris a few years past, with a successful revolution or not, what would follow?