Hard to tell, it being unfinished. There was a firm of architects involved who I'd never heard of - certainly not any of the leading contemporary classicists. They had the grace to sound a bit embarrassed about their jailed client. Tough on them, though - that's the last they'll see of any fees.
Looks like Hoogstraten (who it is said did the preliminary sketches himself) wanted a version of Blenheim. I'd say he's no Vanbrugh.