Ahhhhh the venerable Lister JP, a subject which I am familiar with.
You refer to the overload (excess fueling) protection device on the end of the fuel pump rack, to start the engine you lift the overload stop and move the fuel pump rack as far as it will go in the maximum fueling direction.
When the engine starts, the governor quickly moves the rack, and the excess fueling device reverts back to its normal overload protection position.