throwing this out as an idea:
1777-85 The British come down on the Amertican rebels like a ton of bricks. Greater military luck/skill leads to desperate measssures by the Patriots against real or suspected loyalists, traitors, Indians and supposedly disloyal slaves, and to a very nasty guerilla war. In turn, the anti-American factio n in Britain gains the upper hand and a savage peace is imposed. Prominent rebels are hanged or deported, British lieutenant-governors installed and the colonies run along dictatorial lines and required to pay for the massively increased garrison.
178..handwave..6, an abortive revolution in Naples. Neapolitan Republic is declared, but suppressed by military intervention.
1789/90 Corsica rebels against rising French taxation, declares Corsican Republic
1791 French troops continue to fight a costly war in Corsica while the treasury bleeds dry. Protest at taxes and bread prices. British government meanwhile intensifies steps against "republican sedition". Increasing numbers of people insist that the treatment of the American coplonists was unduly harsh.
1792 France calls the Estates General. Government reform is implemented. British "radicals" view this as a modelo. Increasing dissatisfaction with conservative government.
1793 Protests and riots in many American cities quelled brutally by troops. George III's carriage pelted with stones in the streets of London.
Riots in several British cities.
Radicals elected to Parliament in growing numbers despite efforts to suppress them.
1794 France declares new constitution.
Attempts to arrest several high-profile Radical MPs in Britain.
Heated debate on a "settlement" with the colonies. Continued unrest in America.
France permits the formation of an independent Corsican Republic under French suzerainty.
1795 Sustained boycott campaign of British goods and authorities in Boston, New York, Philadelphia and Baltimore. Peaceful form of protest is met with great acclaim.
Calls for a "Corsican-style" government in Quebec. British troops moved north.
1796 Quebecois anger is met with harsh reprisals, deportations and confication of property. Meanwehile, depleted garrisons in the thirteen colonies find it hard to keep a lid on an increasingly angry populace.
Radical agitation reaches perfectly respectable people. Officers callled on to serve in America publicly resign their commissions. 76th Foot mutinies on news of deployment to Pennsylvania.
1797 George III's reactionary coterie attempt to dissolve Parliament by force. Hilarity ensues. By Christmas, Britain is seeking to hire a new monarch.
For shits and giggles, make Edmund Burke Lord Protector.