Many stories abound of the daring exploits of the RAF's young fighter pilots defying the might of Hitler's Luftwaffe, and of the dogged courage of the men of Bomber Command flying night after night over Germany in the face of flak and Focke-Wulfs, yet little has been written about the pilots who provided the key evidence that guided the RAF planners - the aerial photographers.

Ken Johnson joined No.1 Photographic Reconnaissance Unit as an eighteen-year-old and soon found himself at the controls of a Spitfire high above enemy territory. The PRU aircraft were stripped of all nonessential equipment to increase their performance, because speed and height was their only protection as the aircraft's guns were among those items that were removed.

In this lighthearted reminiscence, Ken Johnson relives his training and transfer to an operational unit, but not the one he had expected. He had asked if he could fly Spitfires. He was granted that request, only to find himself joining a rare band of flyers who took to the skies alone, and who flew in broad daylight to photograph enemy installations with no radios and no armament. Unlike the fighter pilots who sought out enemy aircraft, the pilots of the PRU endeavored to avoid all contact; returning safely with their vital photographs was their sole objective.

As well as flying in northern Europe, Ken Johnson was sent to North Africa, where his squadron became part of the United States Army Air Force North West African Photographic Wing (NAPRW). In this role, he flew across southern Europe, photographing targets in France and Italy.

'A Spy in the Sky' fills a much-needed gap in the history of the RAF and, uniquely, the USAAF during the latter stages of the Second World War.