Christopher Brown
From Tardis Wiki, the free Doctor Who reference
Christopher Brown played Marriner in DW: Enlightenment.
His turn on Enlightenment was not the first time he had played a mild adversary of Peter Davison's on BBC One. Just a few years earlier, he had a recurring role on All Creatures Great and Small, in which he played a veterinary student whose study habits greatly outshone Davison's Tristan Farnon.