My guess would be a faulty coil.
I’ve had a similar problem with my Spitfire. It started fine, but after a short drive the motor stopped, like no ignition (no sparks). After cooling down it started fine again. Changing the coil cured the problem.
Cobber wrote:How ever I used 4 individually fused relays , the reason is if I was to blow a fuse at speed I wouldn't loose all lighting.