Whatever else has changed around him, Michael Troughton has remained a working actor who has outlasted trends, studios and formats. In cinemas, 'Enigma' is the work that stuck — Mr. Mermagen, specifically. 'Doctor Who: Last Christmas' counts among the more visible credits. The oldest credits belong to a different era of the industry. Drama has been the most frequent territory. Neither the cinema nor the television half of the career can be called the side project.