1. Peel and dice the potatoes and boil in salted water.

2. In a small saucepan, mix a small amount of milk with the flour until it forms a paste. Then slowly add the rest of the milk, stirring all the time. Add to the mixture the parsley, salt, pepper, onion salt and margarine.

3. Put the pan on a medium light and when it starts to thicken take off.

4. Away from the heat, add the cooked prawns, salmon, peas and cheese.

5. Return the pan to the light until it is the desired consistency. Pour into an oven proof dish.

6. Meanwhile mash the cooked potatoes with the margarine, salt and Soya milk. When smooth, spread over the fish layer and even out with a fork.

7. Bake in the centre of a pre-heated oven on Gas Mark 6, 200C for 25minutes.