Arthur Christie (1921-2003) was seconded into Special Operations Executive on 22 April 1940 at Aston House, Stevenage, where he was to become one of the founding members of SOE. He was originally trained as an explosives expert, laying charges at the coalface as a miner. It was this expertise that became the reason he was seconded from the regular army into MI6 (R) based at Aston House; this was the place christened "Churchill’s Toy Box." His file is now open at the Public Record Office HS 9/313/1.
The original article can be found at Arthur Christie and the edit history here.