The resignation of Sajid Javid as Chancellor of the Exchequer causes the fall of Boris Johnson's government, and the House of Commons votes for a government of national unity to take its place. Larry the Cat is installed as Prime Minister leading a national government on the ninth anniversary of his becoming Chief Mouser. His first secretary, and successor as Chief Mouser, is Gladstone the Cat, formerly the Mouser of the Treasury.
Joke graphic I've just thrown together for a Discord election game. The Lib Dems in this game are, or at least were, remarkably conservative in nature and very eurosceptic. At one point they were genuinely to the right of the actual Conservatives.