Probably not described as a motor glider when built, but the 1921 English Electric Wren certainly is one, and still flies at the Shuttleworth Collection at Old Warden:
The 1935 Abbot Baynes Scud 3 is in private hands, although its engine is in the Science Museum. I found this out when a friend borrowed it from them for an exhibition at the Farnham Museum (Abbot Baynes was a Farnham company).