Starter Button

These can be found on several surviving cars.  They are engraved "MANUFACTURED BY JOSEPH LUCAS LTD  BIRMINGHAM  ENGLAND".  The rear of the switch has two fairly large screwed contacts, which suggests that they were connected directly by heavy cables to the starter, rather than through a solenoid.  There is no wiring diagram available for the FWD, but there is one for the SD 12/50, which appears to have been identical to the FWD―this also indicates that the starter switch was direct wired. 

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A starter button of the correct type, slightly damaged on the edge of the mounting

Chassis 7317

Chassis 7126

Chassis 7308