He also had a great stage career. I first saw him in the early 80s at Stratford in small Shakespearean roles. I knew he was going to be a star. I recommend The Barchester Chronicles for his star-making tv performance as the nasty but hilarious Mr. Slope (nee Slop). It’s available on Amazon.
I second The Barchester Chronicles. He and the whole cast were great. Alan was also the main bad guy in the “Sweeney Todd” movie.
RIP.