By Aston & Mander & Co. London. Stores reference 13/88.  1942 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 edges and corners and tarnishing of metal parts. Good used condition overall. As used by the Navigator for route plotting in bomber aircraft. Stock code M19424.