Boil the potatoes in water for about 15 minutes. Drain and mash them with the lemon juice and half the butter.
In the saucepan, if fresh fish is used, cover with Babynat follow-on milk, bring to the boil and poach very gently until cooked (about 5 minutes) Drain the fish and break up into pieces with your fingers. Make sure that no bones remain.
Mix the fish and mashed potato then add a bit of pepper. After dusting your hands with a little flour, shape 8 flattened balls.
Beat the egg and milk in a bowl. Dunk each ball into this mixture, then in the breadcrumbs.
Heat up half the oil in a frying pan over a medium heat. When piping hot, reduce heat and place 4 fishcakes in the frying pan. Brown each side for 5 minutes. Use kitchen towel to drain and keep warm while frying the other 4 fishcakes in the remaining oil.