If Princess Alexandrina Victoria of Kent had been Prince Alexander Victor then instead of the Hannoverian crown and the UK crown diverging Hannover would have remained linked with Britain, sharing a monarch and Prussian influence deflected and the German states not united under Prussia.
A British supported Hannover could stand up to Prussian ambitions leading the assorted German states in some loose confederation that would be strong enough to repulse French, Prussian or Austrian aggression without territorial ambitions of it's own.
Maybe a 19th century proto European Union if the created a single market tempting the Low Countries and Scandinavia to associate themselves for access to the German market and UK allowing access to the Empire market.
A British supported Hannover could stand up to Prussian ambitions leading the assorted German states in some loose confederation that would be strong enough to repulse French, Prussian or Austrian aggression without territorial ambitions of it's own.
Maybe a 19th century proto European Union if the created a single market tempting the Low Countries and Scandinavia to associate themselves for access to the German market and UK allowing access to the Empire market.