Looking at the detailed appearance list, IMDB is counting the appearances as the mysterious figure from the 1st and 4th parts of the last Tom Baker story (Logopolis) which by their (IMDB's) dates aired in 1981. Granted his face isn't visible at all in the 1st (that I remember :) and then the standard post-regeneration-here's-the-new-guy quick appearance in the last part.