The Fauvel AV36 was a tailless glider designed in France by Charles Fauvel and which first flew in 1951. Over 100 were built. Whilst this example carries no markings I blieve the identity to be correct making it the former RAFGSA53. A very strange machine that I would love to see in the air.
This photo was added on 23 January 2018, and has since been viewed 46 times.