Master unit, Mark I, from an RAF Distant Reading Gyro-Magnetic Compass, composed of a magnet controlled directional gyroscope and magnetic corrector box, invented by Philip Andrew Cooke and Leonard Charles Bygrave, 1926, unsigned, British, 1940-1945 Master unit 1940-1945
Gyro compass course recorder type B no.540, by S G Brown Limited, London, England, 1940-1948. Used with gyro compass switchboard, type A (1948-365). Gyro compass course recorder type B no.540 1940-1948