Fish pie with potato crust

Name: Fish pie with potato crust
Ingredients: 1kg Maris Piper potato, cut into chunks; good grind of nutmeg; 175ml double cream; 75g butter, plus a little extra for the top; 2 egg yolk; knob of butter; 2 shallot, finely chopped; ½ tsp fennel seeds, lightly crushed; 1 star anise; 300ml vermouth; 300ml fish stock, fresh if possible; 300ml double cream; 200g skinless smoked haddock fillet, pin-boned and cut into 3cm pieces; 200g skinless cod fillet, pin-boned and cut into 3cm pieces; 200g skinless salmon fillet, pin-boned and cut into 3cm pieces; 140g frozen pea; 4 egg, hard-boiled and chopped; small bunch parsley, chopped; small bunch dill, chopped; juice ½ lemon