Cook the potatoes for about 25 minutes in boiling salted water, until soft. Peel while they are still warm Mash and add 20g butter.
Bring saucepan to a medium heat, add the kale with 3 table spoons of water and 50g of butter, cook until tender. Reason for so little water is to keep vitamins contained and because cabbage is 90% water.
Fold the cabbage through the potatoes; bind the mixture together with a beaten egg and season with salt and freshly ground black pepper.
Put the water, lemon and salt in a large pan. Bring to the boil, then simmer for 5 minutes.
Add the hake and simmer for 2 minutes. Remove from the heat and leave to finish cooking gently in the cooking liquid.
Melt 25g butter in a heavy-based pan and sprinkle over the flour.
Stir continuously with a wooden spoon to mix and cook for 5 minutes.
Gradually pour in the milk, stirring all the time, to make a smooth sauce.
Add 290ml/0.5 pint of the fish cooking liquid and leave to simmer for 12 minutes.
Drain the hake and cut into 4 portions. Place on four warmed plates.
Stir the picked basil and the rest of the butter into the sauce.
Place Colcannon in the centre of the plate with the fish on top.
Pour the sauce over half the fish. I think dishes like this look more attractive if the fish is only partly covered.