yer like me Stuart, pictures are nice

I woulda got one last night, but too cold and dark .... still cold now but nice and sunny!
here's one
of the 57 with the factory wiring ... the black wire goes to the ammeter then on to the ign sw, BATT terminal, the purple wire goes to the sw, IGN1 terminal [or START on a V8 sw] ... the resistor and coil both have a green wire to the sw IGN1, the resistor has a brown wire to IGN2
when the key is on the resistor gets power via the ammeter, when the starter is stomped the depressed contact completes the circuit to the small post on the side [note it's below the BATT terminal, so it's simply that the big copper block in there moves down to complete the circuit], the full battery voltage is then put to the coil via the ign sw [which is also getting power via the resistor] - when the starter is released, the full-on power to the coil stops
hopefully that's clear!
Bill