[Malcolm]

Competitor Safety (Q) page 166 MSA Blue Book 2007 Para 8 reads.....

"External circuit breaker.

The circuit breaker when operated must isolate all electrical circuits with the exception of those that operate fire extinguishers. The triggering system for the circuit breaker on saloons should be situated at the lower part of the windscreen mounting preferrably on the drivers side or below the rear window. On open cars.... (I am not typing that bit in as irrelevant to our cars).

Alternatively on cars of Periods A-F (Note; dates range from 1905-1965 and if you are competing a replica 40, it isn't a period car but you may want it to look period for other purposes) the mounting point may be mounted approximately vertically below the line of scuttle on the drivers side.

The location must be identified by a red spark on a white edged blue triangle (12cm base) and the on and off positions marked clearly."

IMO this is unlikley to be changed for 2008.