A former dance instructor and long-time stand-in for Trevor Howard, Tatum's grumpy presence was a pleasure to look for in many British films and TV shows from the Fifties onward. He does actually smile once in a while, too! His real name was John Kenneth Tatham, but he often signed his name both Tatham and Tatum, so it will remain "Tatum" here.

IMDb has him listed as both John Tatham and John Tateham. Almost right...