Poach the fish in salted water for approx. 10 minutes until tender. Drain well and reserve a quarter pinto of the fish stock for the sauce. To make the sauce melt the fat and add the flour. Cook for one minute without browning.

Gradually add the milk, fish stock, salt and pepper. Bring to the boil, stirring all the time, until the mixture thickens. Then add the chopped eggs and parsley. Flake the fish. Add to the sauce, and place in an ovenproof dish. Make up mashed potato as directed on the packet and either pipe for fork over the fish mixture.

Bake for 25 to 30 minutes in a moderate oven 350 F, gas mark 4. Serve hot, accompanied by additional parsley sauce if desired.