Kate O'Mara plays a look alike in this episode as Annabelle 2, but it's not the only time she'll be part of a double act. In the Doctor Who episodes "Time and the Rani", September 1987, she plays a look alike to the Doctor's companion Melanie.
The plane seen here (G-AVSM) is a Piaggio P-166B with a rather unusual configuration. The propellers face rearward and provide "push" rather than the usual forward facing "pull" configuration.