Over 20 years ago now, we saw in NZ a black and white British movie about an old fellow who had a strange uncrontrollable hand gesture, but he'd always do it when others weren't looking, so he'd drive them nuts with "there, I just did it". He was assumed to be nuts, and even visited a physchiatrist who, in trying to prove the guy nuts, proved himself to be a pervert and the guy to be probably the most normal guy in the town. He also invented a new mousetrap with a cooking pot -- quite hilarious. We were captivated by the moview at the time and have been trying to find it ever since. Never seems to have been on TV here, but we have no clue what it might be called. Would be thrilled to learn the tile and to find it! There is a possibility that the lead character was Michael Hordern (??) (or a close look-a-like), but we can't find the likely film in the filmography.

My British sources on the Internet suggest that this might be a 1981 episode called You're All Right, How Am I? from the TV series BBC2 Playhouse.