This cold start is the CAV Thermostart, it is a heater plug, that is held on for the specified time, at which point a ball valve open allowing diesel through, this catches fire, this is the point you start the engine, the flames are then sucked into the engine. A very common type of cold start device and works well, usually the first time.
The Start Pilot pump was fitted to the MK, I do not recollect it on the MJ, long time since I was working on them now, but have never had to use a Start Pilot cartridge on a Bedford. also a MK had an electric fuel pump so the instructions on an earleir post are specifally for a MJ