The BIG difference between the UK and the States, is that in the US as soon as you have "radar contact" from Tracon or a centre, you are automatically cleared through all class C airspace (US equiv of our D). If for some reason they want you to remain clear they will either vector you around it, climb you above it, but vary rarely tell you to remain clear. They may hand you off to the Class C airport tower while in their zone, who will then hand you back after you're clear. Same goes for US military bases, tracon and the military controllers work closely together, so you find that you'll get handed from tracon to the military controller, back to tracon.
Its rare to get a "freecall" and NOT be handed off. The only time I have experienced it is flying in mountains where they lose either radar or radio cantact, and can't pick you up again for a while. Could be becasue they don't restrict PPLs to stupidly low altitudes, Give me 10000' rather than 1800' any day
Cheers
EA
