London Gliding club operated at Dunstable during Easter 1940 and several club machines flew with their civilian owners up to a 2,000 ft limit as a trial for training RAF personnel.
fighter command | gliding club | london gliding | 1940 | 0988 | Flight Archive
At that time the gliders had not been impressed into service. That did not happen until after the glider assaults of May 1940 became known.
Regards
Ross