Grease a 15 x 23 cm/6 x 9 in shallow tin.
Sift the flour, salt, black pepper and 1/2teaspoon of the cayenne into a bowl.
Rub in the butter or margarine until the mixture resembles fine breadcrumbs.
Stir in the grated cheese, then knead well to make a firm dough.Knead lightly, then press the dough evenly into the prepared tin.
Cover with an even layer of the peanuts and press them well into the mixture with the back of a metal spoon.
Sprinkle the remaining cayenne over the nuts.
Bake the mixture in a moderate oven (180C, 350F, gas 4) for 25-30 minutes.
Cut the hot mixture into fingers and leave in the tin for a few minutes before transferring the fingers to a wire rack to cool completely.