Tried several things today, firing up the pump with the ignition doesn't work, it pumps for a few seconds (to prime it?) then stops, presumably waiting for the engine management to fire it up again.
Eventually settled for disconnecting the fuel line at the fuel rail (it was the hose on top with a union joint) and using a 12V battery to directly power the pump.
This meant I had anything that could produce sparks etc at the opposite end of the car from where we would get the fuel. Bit of a pain but the pump took ages (at least 10 mins) to fill a 20 litre Jerry can.
The photo shows the two connector pins I used to fire the pump up. The second set of pins closer to the camera are for the fuel level sender