On reflection, with better specs on and prompted by a PM . . . , I think what appears at 26s in the Pathe film is a Varsity. It therefore could be VX835 Napier's engine test bed. According to Putnam's Vickers Aircraft since 1908 it would have been fitted with a Napier Eland NE16 on the starboard wing. A bit before my time but I do remember the Convair N340EL.