Indeed, sorry, from the dates that should have been obvious (my only defence being that I was distracted by an eczema-covered oik, sitting next to me in the library, muttering to himself. He then proceeded to scratch himself vigorously releasing an odour - which, in the interests of allowing people to retain the contents of their stomachs, I shall merely describe as being most distinctly unlike a rose).
The site dates means that it misses out most of the Battle of Britain and the 'Second Blitz' - the V1 and V2 strikes (when Hatfield was fatally struck by the rarer air-launched V1's)
A description on p180 of 'DH - An Outline of de Havilland History' by C Martin Sharp, indicates that the Hatfield factory was, as to be expected, very much a target (even though the DH.98 Mosquito only made its first flight in November 1940):
"...there were many long interruptions all through that autumn*. Bombs fell within a mile of Hatfield factory buildings on one day in every five, sixty eight high-explosive bombs in one hundred days, so that one week nearly a quarter of the working hours, night and day, were spent in the shelters."
As far as the German spy dropped near Salisbury Hall (on 13/05/1941; arrested the next day and executed in December - p183) is concerned, so far I'm not aware of any information that his presence near the Mosquito secret works was anything other than coincidental.Introduction to the Phases of the Battle of Britainhttp://www.rafmuseum.org.uk/research/online-exhibitions/history-of-the-battle-of-britain/introduction-to-the-phases-of-the-battle-of-britain.aspxhttp://www.hatfield-herts.co.uk/warmem/ww2Kciv.htmlhttp://www.flyingbombsandrockets.com/