Interestingly enough, on the listserv PIPORG-L, there is a thread going on entitled "Famous People who play organ." The late British actor and comedian, Dudley Moore, was mentioned as one of them. I had no idea he was so talented at the keyboard, so I looked him up, and sure enough, his bio states that he was an accomplished pianist and organist in his youth, and studied music and composition at Magdalen College, Oxford University, where he was an organ scholar.
This YouTube video shows how talented Moore was at the piano. Here, he is improvising in the style of a Beethoven piano sonata, throwing in elements of the famous whistling tune from Bridge Over the River Kwai.