Peel and quarter the potatoes then place in a large pan of salted boiling water.
Bring the potatoes back to the boil then simmer for 20 minutes until the potatoes are soft.
Drain the potatoes, then add them back into the pan with the butter. Add the white pepper then mash until the potato is incredibly smooth.*
Tip the mashed potato into a bowl and leave to cool for an hour then cover and refrigerate for at least 2 hours until the potato is cold.
Drain the salmon and mix into the cold potato and the parsley leaves with a fork until evenly dispersed.
Shape the fishcakes into patties of equal weight, about 125g, then place on a plate and put back in the fridge to settle for half an hour.
Arrange the flour, beaten egg and breadcrumbs into three separate bowls, then remove the fishcakes from the fridge and coat each fishcake; first with a light dusting of flour, then with the egg, then the breadcrumbs.
Pour the olive oil into a wide heavy based saucepan and heat until sizzling. Then turn the heat down to low.
Shallow fry the fishcakes in two batches, 5 minutes on each side, spooning some of the oil up the sides of the fishcakes to ensure they are golden all over, then place on kitchen towel to absorb the excess oil.
Serve the fishcakes with a light salad and plenty of brown sauce.
These fishcakes freeze very well so make a huge stash for emergencies and re-heat in the oven.