In 1940, the RAF was concerned that radar (the UK Chain Home system) might not detect troop-carrying gliders made of wood that the Germans could use in an invasion of England. To check this, Wills and some other UK glider pilots were towed out to sea in wooden gliders from a field near the Radar station at Worth Matravers on the coast south of Bournemouth . The gliders acted as over-sea radar targets and then glided back to land in the field. However, on one flight on returning over the sea to the field it became evident to Wills that his angle of glide would not get back over the cliff. Because from flights over Dunstable Downs he was well aware of so-called ridge lift where air rises over an up-slope, on arriving below the cliff top he was able to use the rising air due to the off-shore wind over the cliff to gain enough height to land safely back in the field. Meanwhile, people rushed to the spot last seen on the radar, to peer anxiously down over the cliff edge to look for a crashed glider, while Wills looked down from above.