Concorde Engine Instrument

This is probably a prototype of an instrument which Indicates the gas temperature in the Jet pipe on the dial scale and digital counter.
The production instrument has additional displays:
Loss of electric power supply to the gauge shown by a red and black striped flag across the digital counter.
Loss of EGT information to the gauge is shown by the pointer being at 0°. At a temperature colder than -5°C at the EGT thermocouple the EGT gauge pointer will indicate 0° and a striped flag will appear across the digital counter.'