1. Put cod in saucepan with milk and bay leaf. Bring slowly to boil and poach gently for 10 minutes or until fish flakes easily.
2. Trim and slice leeks and blanch them with broccoli for 3 minutes in boiling salted water. Drain.
3. Lift out fish, remove and discard skin and bones. Flake fish. Strain and reserve milk.
4. Put leeks and broccoli into a pie plate and add the cod and shrimp.
5. Melt butter in a saucepan, add flour, and cook, stirring, 1 minute. Remove from heat and gradually blend in the reserved milk. Bring to a boil, stirring constantly until thickened. Simmer for 2-3 minutes. Season to taste and pour over the pie filling.
6. Grate the pastry using the course holes of a grater (be sure pastry is well chilled to do so). Sprinkle with the the grated cheese. Bake 400 degrees F for 25-30 minutes.