This isn't really the right thread for this, but there isn't a right thread for this, so here you go anyway.
But: A Jacobite Phantasm
Kings of Great Britain
1714-1727: George I (House of Hannover)
1727-1760: George II (House of Hannover)
1760-1789: George III (House of Hannover) [1]
1789-1793: George IV (House of Hannover) [2]
Protector of the British Commonwealth
1793-1805: Charles James Fox (Radical) [3]
Kings of Britain
1805-1808: Henry IX (House of Stuart) [4]
1809-1826: James IV (House of Stuart) [5]
Kings of Great Britain and Ireland
1826-1827: Frederick I (House of Hannover) [6]
1827-0000: Augustus I (House of Hannover)
[1] - George III was the first British monarch to abdicate voluntarily, for a given value of 'voluntary'. He had been prepared to throw in the towel after losing the Thirteen Colonies in the late 70s and early 80s, but had been dissuaded. Now, several years later, he was becoming more and more aware that his mental state was becoming less stable due to the stresses of office (some historians have claimed that he had a condition known as 'porphyria' as well as mere stress, but obviously they cannot prove it without his body). And as London erupted in 1789 with the fires of riots and protests, which began in sympathy with the Parisians and continued with more of a focus on the plight of the English poor, George III had had enough. He presented his abdication to Parliament in a historic and unannounced Speech from the Throne, and after a long debate on whether that was even legally possible, Pitt the Younger allowed him to retire to his beloved Buckingham House.
[2] - To tell the truth, the Revolutionary ferment before the Abdication had been a thoroughly insipid brew, and was widely expected to die down naturally - but the Abdication had shown the Radicals that they could remove anybody they pleased if they stuck at it, so well-known events such as the Battle of the Strand, the Four Days of Southwark, and the September Affrays ensued with heightening viciousness and frequency. George IV was much less popular than his father - a boorish drunkard with a taste for women that no right-thinking bourgeois Protestant would condone. So the right-thinking bourgeois Protestants stayed at home rather than fight the Revolutionaries. After the torching of the Houses of Parliament - during a well-attended sitting - by the Horse Guards in 1792, events took an even more dangerous turn, and the 504 ensuing by-elections were mostly won by Radical or Whig candidates. They passed extreme laws based on those promulgated by the French, and imprisoned the Royal Family in 1793. A dictatorship under Charles James Fox, a moderate Radical, was announced, and the British Terror claimed its first victim in Burgher George as he was guillotined the following Spring.
[3] - Now that a Government sympathetic to Revolutionary ideals had been put in place in Britain, there was pressure from Paris to contribute to the defensive war against the Imperial powers. This was, of course, made more difficult by the fact that most of the Generals were on their way to the scaffolds for the crime of being aristocratic, but the Navy was not affected quite as much due to the fact that reaching a high rank in that Service required some form of intelligence or skill, a system unique in Britain at the time. So newly-promoted Admiral Cochrane (himself an aristocrat, later inheriting the Earldom of Dundonald) performed sterling work for his Radical allies in keeping the French trading routes open and blockading much of the Mediterranean and North Sea coastlines of the anti-Republican Coalition. Back home, Fox was introducing major reforms, such as the emancipation of Catholics and Slaves and the timely abolition of the House of Lords. But Fox was becoming unpopular in the country at large as his earlier liberal principles devolved into the usual reign of terror that accompanies Revolutionary dictators - and you're never quite sure whether the Terror refers to the fear of Counter-Revolutionaries or the fear of execution. Eventually, Fox even lost the support of the French, as their political wheel of fortune landed them with 'Empereur Jacques Macdonald' in 1804, and the Radicals in Britain were left without allies in Britain or elsewhere.
[4] - Emperor Macdonald was, as the name implies, a Scotsman, son of an exiled Jacobite who had settled in France. Naturally, the great General and hero of battles too numerous to mention wanted an ally on his seaward flank, so in 1805, he paid his homage to the Pope (still a keen supporter of the Bourbons) and pacified him by offering the British throne to one of his Cardinals, Henry Benedict Stuart, who was officially called 'the Cardinal Duke of York' in the Papal States. The Pope jumped at the idea of finally returning England and Scotland to the fold, and pressured the reluctant Cardinal to accept. He duly did so, and while the tiny Channel Fleet (weakened since nobody was expecting treachery from the French while Britain was ensuring their colonial trade got through) was on manouevres in Biscay, Cardinal York and 6,000 French troops landed in Medway. York's banner rallied most of the Old Tories who still bore a flame for the Stuarts, and most of the Hanoverian supporters, who were just desperate for a King at this point, no matter how Catholic. There was very little opposition from the decapitated Army on the way to London, and once the Cardinal had been crowned and Fox cast into the Tower, there was no point in resisting.
[5] - Henry IX, 80 years old when he became King, did not last long, but he did manage two major things on a domestic level: as Head of the Church of England, he healed the Schism with Rome (although there are a few hundred congregations of Continuity Anglicans to this day); and as King, he was released from his vows of celibacy and engaged to Emperor Macdonald's eldest daughter. Despite the fact that the age difference put off many of the more squeamish Britons, this match did what it was supposed to do, and Queen Anne-Charlotte was pregnant by the time Henry IX died in 1808. Now, James IV was actually born in April 1809, but his reign is backdated to 1808 for odd legal reasons. He was never to rule in his own right, though, as Emperor Macdonald was eventually defeated by the Anti-Imperial Coalition in 1818, despite the presence of four divisions of battle-hardened British infantry arriving at Waterloo about midday - they were too late to save the Emperor, and Brits have been mocked for their lateness ever since by our Continental cousins. Anyway, James IV, as a child, enjoyed the acquiescence, if not the support, of most of the political Establishment, who foresaw that they could control him more easily than they could the Elector of Hannover, who had served as a Field Marshal in the Austrian Army and physically killed British soldiers during the Macdonaldic Wars.
[6] - In 1826, though (when James IV was 17 years old and going through an awkward phase of adolescence which made Prime Minister Londonderry think he was a complete dickhead) Elector Friedrich, Duke of York and Albany landed with a few hundred Guelphic Legionaries and marched on London, which was at that point getting quite bored of being the focus of political life for the first and only time in that city's lengthy history. After the four-day Battle of Ilford, the capital was open for the taking, and the House of Hannover was restored under King Frederick I. James IV was reduced to 'Duke of Albany' and kept under armed guard for the rest of his long life. But Frederick died a year later and was followed by his more amenable brother, Augustus. All other brothers of that generation were either killed in action or executed by Charles James Fox, of course, and all of the surviving sisters are elderly and childless. It is unclear whether the King's cousin, the dashing (and Brit-killing) Duke of Brunswick, will succeed, or whether King Augustus will legitimise his handicapped son. This is a thing which kind of needs to be addressed.Or we could have another Civil War. Either/Or.