I have heard many people say:
He is a London-return doctor.
Is -return as a suffix valid, meaning to have returned from some important place?
Thanks in advance.
I agree with Jeff Morrow's comment. I am 61 years old and have been speaking, listening to, and reading English all my life, and I don't recall ever seeing this wording. I'm an American so perhaps it is local to some other English-speaking country. If I read a sentence like your example I might be able to figure out what it means from context, but otherwise I would be left to guess.
"a London-returned"
, brings up a bunch of results, but they all seem to be from Indian sources. That's at least well-attested.