By Aston & Mander & Co. London. Stores reference 13/88. 1940 dated. 'Capt. Field's Improved' boxwood parallel rule with brass fittings. Approx. 45cm/18" in length x 7.5cm/3" wide when closed. Clear Air Ministry and crown markings. Some minor wood loss/chips at the corners and tarnishing of metal parts. Named to the owner. Good used condition overall. As used by the Navigator for route plotting in bomber aircraft. Stock code M21359.