It was used to test the tailless design that he had suggested as a means to convert tanks into temporary gliders so they could be flown into battle.
[1] A 1/3 scale prototype was built entirely of wood in 1943 by Slingsby Sailplanes at Kirkbymoorside, and the Baynes Bat made its first flight in July 1943 possibly at the Airborne Forces Experimental Establishment at RAF Sherburn-in-Elmet or most likely at RAF Snaith a few miles away, where other AFEE projects where also being tested.
[1][2] Tests were successful, but the project was abandoned because a suitable tank was not then available and a decision had been made to develop gliders which could carry heavy equipment within their fuselages.
The strategists were not convinced of the practicality of retrieving large numbers of Baynes Bats from the field, but in wartime this was not a critical factor.
The Bat was sold as surplus in October 1946 and entered on the British Gliding Association register in November 1947.