CADFAEL! mystery solvin monk from the 12th century! sir Derek Jacobi(who i feel has possibly the greatest last name ever). him saying "one corpse too many" made me really happy. Sherlock Holmes for back in the day? he even has the same thinking pose.
also of note is that the dude that played Reginald Musgrave in the Granada Adventures of SH is in it. can't wait to see what constitutes the science of deduction of the 12th century!