I'm still unsure about the whole Germany-Austria thing. Austria believed it was their inherent right to rule over all of Germany, and indeed for a long time it seemed that they could be the unifiers of Germany into a proper state. They had a long-standing feud with Prussia and weren't going to let Prussia get Germany just like that.
The PoD changes these perceptions somewhat. ITTL Prussia is the heroic vanquisher of Napoleon. At the best, Austria may claim co-rulership of Germany with Prussia, which this settlement implements. Anyway, in view of late criticism, I've decided of modifying the settlement, in order to better the share of Austria.
Austria gets direct rule over Bavaria. Rhenish-Palatinate would be surely split up (likely to Baden, or becoming an independent state). I am struggling to decide whether Franconia and Swabia would be given to the Habsburg as well, or given to Baden and Wurttenberg, or become an independent state. Suggestions ? How much of Bavaria must go to Austria, in order to balance Prussian gains ? Old Bavaria, or Franconia and Swabia too ?
Italy would be little compensation to them - Italy proved troublesome time and time again - heck, in a few decades the entire area in essence rebelled in favour of a united ethnic Italian state, and conquered Austrian land as they went. Rather than being a fair swap for Austria, Italy would actually be a chain around their ankles.
This is wholly hindsight. Not a relevant concern in 1815. Italy had been a meek and valuable French possession/satellite under Napoleon. They had not rebelled in 1813 as Germany.
Also, a number of countries would have been unwilling to let Austria gain so much influence over Italy, too.
Which countries ? Prussia is getting its own share. Russia has all of Poland, and doesn't mind anyway. France is an occupied country and has not a voice in this Congress of Vienna.
It's a bit of double standards, really. Austria wanted land but wasn't prepared to make a deal if it involved Prussia getting a lot of land. Prussia wanted land but wasn't prepared to make a deal if it involved Austria getting land.
ITTL greater concern over aggressive France breaks the deadlock, they accept the deal, and both get aggrandized.
Even in 1815, 100 years after the Hanoverians had taken the British throne, they still viewed themselves as essentially German, and were disliked for it in Britain.
This is essentially uncorrect for George III, who was born in England, spoke ENglish as first language, and never visited Hannover in his long life. And this is surely completely untrue for the Prince Regent, who was in charge in 1815. George IV was unpopular for wholly different reasons, and surely cared for Hannover much less than Gibraltar or Malta.
While you might trim a little bit off Hanover to make concessions easier to bear in the Congress of Vienna, saying "we're dispossessing you of Hanover, have a bigger country in exchange" would be an insult. It would be like saying to the Prussian Kings, "well we're not going to let you have Germany. That's Austria's patch. So would you please surrender Prussia? We'll give you Russia in exchange". I mean, the proportions are different but that is essentially what is being asked here.
Trading thrones of minor and middle states was fully-established diplomatic practice in Europe since the Peace of Westphalia, if not earlier, and was seen as perfectably acceptable and not insulting or humiliating in the least, if the Great Powers agreed upon it and some degree of fairness was involved.
The new country would be tempting briefly in terms of its wealth, but that ultimately wouldn't make up for the fact that George III was a victorious monarch - in fact the victorious monarch of the Congress, considering the UK had been the sole state to constantly oppose the French - and yet he was having his homeland taken off him to make his ally happier. Not to put too fine a point on it, but it's the kind of insult which could break alliances.
The place where you grand-grandfather was born and you never cared to visit or give serious notice except to draw some extra troops from is no place to call your homeland, sorry. George III is a raving lunatic in 1815, the Prince-Regent calls the shots that the Parliament allows him to call, and very very few leading British politicians in 1815 give a rat's ass about Britain keeping a personal union with Hannover.
The same can be said of the Dutch - the Dutch already had a monarch.
Say more of an hereditary president for life, with several significant interruptions, and exiled since 1795. Hardly the same prestige as a true monarch.
Indeed, the Prince of Orange had been on Wellington's staff at Waterloo.
You mean him, or his son ?
And I'll point out that the British felt little support for Hanover, aside from the fact that it respected the King's German Legion as very good soldiers. If you do try to swap Hanover's ownership around, it's a deal to be done with George III himself. Hanover isn't British and the British don't want it, so they have no interest in bartering for it. As others have again said, Britain didn't even want the commitment of being given Dunkirk to look after.
You mean the Prince-Regent. George III in 1815 is busy speaking to trees. And George IV didn't care fig over keeping Hannover. If he can somehow wrangle some extra cash from the deal to support his extravagant lifestyle, he would gladly sell Hannover off.
If you deem that the British government would prefer to have Prussia annex most of Hannover, with still setting up United Netherlands as a satellite under the Oranges, that's fine by me.