Charlie Bigham's fish pie recipe

Name: Charlie Bigham's fish pie recipe
Prep time: 30 min
Cook time: 1 h 30 min
Total time: 2 h
Cuisine: European, British
Ingredients: 500 g skinless salmon fillet, cut into 4–5cm (2 inch)chunks; 600 g skinless hake, cod or haddock fillet, cut into 4–5cm(2 inch) chunks; 175 g young spinach, tough stalks removed, or baby spinach; 25 g dried white breadcrumbs; 60 g mature cheddar, finely grated; 2 tsp. chopped flat leaf parsley leaves; 100 g butter; 90 g plain flour; 750 mL milk; 250 mL double cream; 240 g skinless smoked haddock, cut into 4–5cm(2 inch) chunks; juice of 1 lemon; sea salt flakes and freshly ground black pepper; 1 .6 kg floury potatoes, preferably Maris Piper, peeledand cut into even-sized chunks; 70 g butter; 125 mL double cream; 2 large egg yolks, lightly beaten