Whomever it is, I hope they go a bit older next time. This thing with the Doc's getting younger and younger is ridiculous. Maybe Martin Clunes? (love Doc Martin)
They say an older actor wouldn't be able to keep up with the frantic pace of filming a whole season and I believe them. Now if we only get seven episodes a year, I think an older actor could be cast in the role.
Besides, Eddie Izzard is
a marathon runner.