Code: M21538
By A. G. Thornton Ltd. 1940 dated. 'Capt. Field's Improved' boxwood parallel rule with brass fittings. Approximately 45cm in length x 6.8cm wide when closed. Clear Air Ministry and crown markings. Light scratches/marking but in very good overall condition. As used by the Navigator for route plotting in bomber aircraft. Stock code M21538.
