Hi Bush 65,
I have had hgv's and other land rovers, so know how they work, from ignition switch,on early diesel engines their used to be a button on the side of engine for cold start. the top wire goes to starter motor, bottom wire goes to heater plugs, and the wire on the side goes to switch in cab, no wires
going to ignition switch. and as mentioned before their is a click from starter motor when button is pressed.

Two photos of the back of fuel pump.