Welsh-born actor Gerald Hamer was one of a legion of British actors working in Hollywood in the 1930s and 1940s. A character player who could melt into any part he portrayed, he might be totally forgotten today except that he has the distinction of playing one of the most sinister roles in any of the Basil Rathbone/Nigel Bruce Sherlock Holmes movies, the part of Potts/Tanner/Ramsden in The Scarlet Claw. A true psychopath, with none of the suave villainy of, say, George Zucco or Henry Daniell in their portrayals of Holmes' antagonists, Potts is memorably crafty and savage in a series that usually prided itself on glib-tongued villainy. It's also a tribute to Hamer's skills as an actor that the producers saw no reason not to use him in roles in four other films in the series, as John Grayson/Alfred Pettibone in Sherlock Holmes in Washington, Kingston in Pursuit to Algiers, Major Langford in Sherlock Holmes Faces Death, and Mr. Shallcross in Terror By Night, the latter two after The Scarlet Claw. A British stage veteran from 1916, whose theatrical credits included King Henry VIII, The Taming of the Shrew, and The Admirable Chrichton, Hamer worked in Hollywood from the mid-'30s until 1951, his other thrillers include Bulldog Drummond's Bride and The Lodger, but he also slipped into more benign settings, such as the cast-of-hundreds war relief effort Forever and a Day and George Stevens' Swing Time, equally well.