Been and had a look, it's all fixed, so here's another one for the list...

The charging wire from the alternator back to the battery had come loose off the connector
I reckon it's actually gradually broken off as the wires looked rusty when I peeled the insulator off.
Worst, the insulator was all burnt, either because it had been touching the alternator case and shorting to ground, or, due to the heat from the exhaust manifold

Anyway, brand spanking new red cable now in place

Thanks for your helps lads