I'd imagine naval battle in the Solent leads to the attempt to land troops at Southampton and Portsmouth. Portsmouth fails outright, Southampton succeeds to a limited extent but they fall back and retreats to the Channel Islands which they manage to hold with their combined French and mercenary fleet.
As a side note, how about marrying William to one of the legitimized Sussex line?
Alright interesting, the King Consort will win the day I thinkj at Portsmouth and later on driving them from the Channel. And as in the Prince of Wales to a granddaughter of the Duke of Sussex? Is that the smart option? Given this was still the age of political alliances
The line of succession c. 1855 ...
-- Elizabeth II
--- William, Prince of Wales
--- Frederick, Duke of York and Albany
--- George, Duke of Clarence and St Andrews
--- Georgiana, Princess Royal
--- Adelaide
-- Alexandrina of Kent
-- George, Duke of Cumberland and Teviotdale
--- Ernest Augustus
--- Frederica
--- Marie
-- Augusta, Baroness Truro*
*- assuming we still legitimise the Sussex children
Looking good, Drina to Tsar Alexander II?