On the evening of July 6, 1940 eight aircraft from 99 Squadron departed Newmarket at 21:45 including Wellington IC R3170 piloted by Bob Willis destined for Cologne Germany. In very poor weather conditions they were forced to abandoned their primary target and, on their return, attempted to bomb Schiphol Airport in Amsterdam. Their left engine was hit with flak and the aircraft burst into flames. Bob managed to belly-land the aircraft in a field in Haarlem coming to rest partially in a row of farmers cottage on a roadside. The rear gunner Sergeant Sexton died in the crash and subsequent fire, but the remainder of the crew, P/Os Willis and Perkins and Sergeants McArthur and Scanlon survived. Pilot Officer Perkins's foot was injured in the crash so they split up with Bob staying with John Perkins and McArthur and Scanlon able to travel more quickly to the east.
source: The Bob Willis Story, Bill Dawson