By Hughes & Son Ltd. 'Capt. Field's Improved' boxwood parallel rule with brass fittings. This is the less commonly found small version of the rule. Approx. 30cm/12" in length x 6.5cm/2.5" wide when closed. Clear Air Ministry and Crown markings. A bit grubby and faded. Brass fittings tarnished but would clean well if desired. Some relatively minor wood loss at the edges in places (see photos). As used by the Navigator for route plotting in bomber aircraft. Stock code M19103.