Matt Smith should play Campion
I think it's mainly when he starts to wear Amy's glasses post-Angels, but I think Matt would make a great Campion. It's a great detective series set in the 20's/30's and Peter Davison played the part well in the 80's. It would be cool to see a new version of it - kind of counterpoint to Miss Fisher's Mysteries and Sherlock I guess.
I just like to see Matt back on TV again - I'll be tuning into The Crown when it airs, but it would be nice to see him in a mystery series too.