preheat the oven to 190C, fan 170C, Gas 5
hard boil the 4 eggs, then peel and cut into quarters
peel the king prawns and keep a few of the heads to decorate the pie
heat the milk in a wide pan until just simmering; add the salmon and poach in the milk for 3 minutes, then add the smoked kippers and poach for a further 3 minutes. Remove the fish with a slotted spoon and flake into large chunks. Poach the prawns in the same milk for another 3 minutes then remove with a slotted spoon
pour 1 litre of the poaching milk into a jug and set the rest aside to use in the mashed potatoes
peel the potatoes, place in a pan and cover with cold water. Bring to the boil and cook until very tender
to make the white sauce, melt the 100g butter in a pan, then add the flour and stir until smooth, cook stirring constantly for 3 minutes. Next, over a low heat, add the litre of warm milk, a little at a time, stirring constantly, until you have a rich creamy sauce. Simmer gently for 5 minutes then add the mustard and seasoning
when the potatoes are ready, drain very well and whilst still hot mash with the 2 tablespoons of butter until very smooth. Gradually add the hot remaining poaching milk to the potatoes and mix well. You might not need all the milk. Season to taste
butter a deep baking dish and spread a small amount of the white sauce on the bottom. Add the fish, prawns and the egg quarters, then the remaining white sauce. Top with the mashed potato and drag a fork across the top for decoration
brush very generously with beaten egg and decorate with the reserved heads of the prawns
bake for 45-50 minutes or until the top is golden brown and bubbling
This pie can also be served cold but I think that it tastes better piping hot
8 servings