In a small churchyard in a sleepy Sussex village, lies a young RAF squadron leader, Ronald Sansom who died in an air crash in 1942, on the banks of the River Wye in Wales.  At the request of Winston Churchill, the circumstances of the crash, and the death of Squadron Leader Sansom, his crew and four civilian observers remained secret until long after the war was over. But what was the secret, and why was it so important?