Accent may play a small part, but I dare say visual performance will play a greater role.
Incidentally, Nat, I believe Bob Mortimer is from boro, Vic Reeves is from Darlington. they both met in London where Bob was a solicitor. I too am from Stockton on Tees. other comic exports would also include Roy Chubby Brown.
As for accents, I've lost the smoggie accent, after spending 10 years in wales I've got a tees-taff accent. has it hindered me? I don't think it has.