In relation to intercepting the Canberra, English Electric's Chief Test Pilot, R.P. Beamont, recounted that in 1951 he flew a Canberra B.2 through US airspace at 50,000 ft. while en route from Gander to Baltimore.
USAF F-86 fighters attempted to intercept it but, embarrassingly, ran out of "puff" at 42,000 ft. The Canberra further annoyed the Americans by refusing to disclose its height to ATC, on the basis that this was classified info!
I think it's safe, on the basis of this account, to say that a Vampire would have fallen well short of a Canberra at its maximum cruise level.