Ultimate fish cakes

INGREDIENTS

• 125ml mayonnaise
• 1 rounded tbsp capers , roughly chopped (rinsed and drained if salted)
• 1 rounded tsp creamed horseradish
• 1 rounded tsp Dijon mustard
• 1 small shallot , very finely chopped
• 1 tsp flatleaf parsley , finely chopped
• 450g skinned Icelandic cod or haddock fillet, from a sustainable source
• 2 bay leaves
• 150ml milk
• 350g Maris Piper potatoes
• ½ tsp finely grated lemons zest
• 1 tbsp fresh white flatleaf parsley , chopped
• 1 tbsp snipped chives
• 1 egg
• flour , for shaping
• 85g fresh white breadcrumbs , preferably a day or two old
• 3-4 tbsp vegetable or sunflower oil , for shallow frying
• lemon wedges and watercress , to serve