I can't say I find the idea very appealing, although the source is a nice one to bring up when people assert that there was no such thing as "Scotland" in the 19th C (which
has happened to me before).
Or more generally "Don't put any sort of power or influence in the hands of British republicans!"
Although the scenario is actually very fascinating. I'm still mulling it, so may I ask your expert opinion:
George IV (or maybe William) is replaced by a British version of Charles X who utterly refuses to budge from strident reactionism, clamping down through secret police and the established church. He gets a France 1830 on his butt at about the same time as France: he can't make parliament dance to his tune (if he's reactionary enough, that could be over Catholic emancipation; if not, suffrage, or just something incidental), so he tries to rule without it: middle class liberals whip up a journalistic fenzy, hungry out-of-work people start throwing stones at policemen, students go onto the streets with flags wrapped round themselves, etcetera etcetera, and he abdicates and decamps. After some horse-trading in London and no William III presenting himself, a republic is established.
Whither Hanover?