Thank you both for your thoughts.
I can step you through my actions so far if you have the time.
I unbolted the lift pump first, it does not leak and the manual lever produces a good pulse. The sump still drained diesel, l disconnected the injector lines from the top of the Bosch pump and the diesel still drained from the sump plug.
With the fuel tank cock shut the flow stopped.
I will look for the side cover plate of the pump and check what happens
Did anyone look at the online auction catalogue.