Lay the kipper in a shallow dish and pour a generous ½ pint (275 ml) of boiling water over it to cover it, then leave on one side for 5 minutes: after that, drain (reserving the water) and flake the fish, discarding the skin, head and bones.Now strain 5 fl oz (150 ml) of the reserved water into a jug and keep it on one side.Next heat half the butter in a saucepan and fry the onion for 5 minutes to soften before stirring in the curry powder and the rice.Cook for 1 minute then add the reserved strained stock. Bring to simmering point, cover and cook over a low heat until the rice has absorbed the liquid and is tender – about 15 minutes.Next melt the rest of the butter in a separate pan, add the lemon juice and cook the mushrooms till tender (about 3 minutes).Then add the contents of the pan to the cooked rice together with the flaked fish. Peel and chop the hardboiled egg and add that to the rice as well, then fork everything in carefully, trying not to break up the fish.Taste and season with salt and pepper as required.Serve in a warmed dish, garnished with parsley and an extra knob of butter. (I like to serve this with a sprinkling of cayenne, too.)