Heat the fat up in a chip pan or a deep fat fryer.
Peel the potatoes and cut into large, thick chips. Then rinse and dry them using kitchen towel.
Fry the chips in the oil until soft but not coloured, which should take around three minutes.
Drain and shake the chips well and then set to one side.
Put some flour onto a plate and coat the fish fillets thoroughly with the flour.
To make the Best Bitter batter, put the flour, bicarbonate of soda, salt and pepper into a bowl then gradually add the Best Bitter. Stop when you have a thick coating of batter. Whisk to remove any lumps to make a smooth batter. Add the lemon juice, then mix again thoroughly.
Take one fillet of haddock at a time, holding it by its end and swirling it around the batter until it has a good coating, then plunge it into the hot fat immediately.
As soon as the first fillet has started to crisp, add your other fillets one at a time, taking out the first ones as they cook. This should take 6 -10 minutes depending on the thickness of fillet. Place onto a baking tray and keep warm in the oven.
While the fish is in the oven, add your chips to the hot fat again and cook until crispy and golden in colour.
Serve with tartare sauce, mushy peas and a pint of Golden Sheep.