The best advice in France is to climb above 1500 feet ASFC as soon as possible, and to stay there. Do not get too 'hung up' about the precise definition of 1500 ASFC. The intention is that you should be high enough above the ground to let a couple of us go underneath you very fast.
Thanks. This makes sense.
Presumably therefore you don't actually need clearance to cross them, not that I intend to very much.
QDM