In the early 1950s van Geersdaele served in the Royal Air Force.[1] While stationed at RAF Binbrook, in Lincolnshire, he played football for Grimsby Town F.C., managed by Bill Shankly.[1] According to a later colleague, van Geersdaele "toyed with being a professional footballer" after his discharge, and had a trial with Queens Park Rangers F.C.[1] Instead, in 1954 he joined the British Museum.[1]