Mechanical digital hand-wound spring-driven clock, with analogue 12-hour dial showing hours, minutes, seconds and AM/PM, with built-in push-button-operated minute and hour chronograph, the whole employing a constant force escapement by Porte-Echappement Universal SA, for providing a continuous record of Greenwich Mean Time to the Royston MIDAS aircraft flight data recorder system, made by A & M Fell Ltd, London, 1961, being the first production example, serial number E1/01.