Soon after outbreak of Second World War was appointed General Staff Officer at General Headquarters, Home Force Staff dealing with Home Guard in their role of "Invasion of Britain" threat. During this time he enjoyed taking friends to the Depot and showing them the large mass of weapons which had been collected as a result of the Prime Minister's order to fight to the last ditch with any available weapon.

Colonel Gubbins sent Major the Honourable Michael T Henderson to scout around the country for a suitable HQ after the Luftwaffe blitzed the cramped offices in Whitehall Place, Westminster.

Henderson soon discovered that Coleshill, the country estate adjacent to that of his brother, was qualified in all respects (as a potential HQ).  Coleshill's owner was the Earl of Radnor, but only the Earl's two Pleydell-Bouverie sisters and their dogs lived there.