Evening,

This thing is now fixed, assuming a professional bodge could be called a fix! Traced the wiring back to the immo unit where-upon I became daunted by the 1001 wires that appear to be connected to it. So utilised the ignition fed feed I found in the engine bay and connected that to pin 86 on the glow plug relay. To operate the glow plugs, I connected a dashboard switch to the engine coolant temp sensor. Simples

Thanks to Ian and Mark for their interest.

Regards

Pete M