Remove the lamb from the refrigerator about 2 hours before you intend to roast it. Remove most of the fat from the lamb, leaving a thin layer of fat to cover the meat. Leave to stand at room temperature until it has lost its chill. If you are using frozen pastry, allow it to defrost during this time.

Meanwhile, clean the kidneys, remove the skins and cores, then cut the kidneys into 5 mm (1/4 in) dice. Melt half of the butter in a heavy frying-pan and saute the kidneys for 1 minute, stirring so that they brown all over. Drain off most of the fat, then add to the pan the sliced mushrooms, the breadcrumbs, herbs and salt and freshly ground black pepper to taste. Saute for a further 3 - 4 minutes, until the breadcrumbs are golden. Remove the pan from the heat. Pour the brandy over the kidney mixture and, standing well back, set it alight with a match. Let the flames burn themselves out, then leave the mixture until lukewarm.

Blend the pate into the kidney mixture, tnen leave until cold.

Heat the oven to 190°C /375°F /gas 5. When the meat has lost its chill, press the kidney mixture into the space left by the bone. Ease the joint back into shape. Tie it up securely, or sew along the seams with a trussing needle and thread.

Place the stuffed leg of lamb on a rack set in a roasting tin and place in the oven for 45-60 minutes, depending on how well cooked you like your lamb. The lamb will only be partly cooked at this stage. Remove it from the oven and cool completely.

Heat the oven to 230°C /450°F /gas 8. Remove the string or thread from the cold lamb and spread the lamb with the remaining butter. Roll the pastry to a rectangle, about 35 x 40 cm /14 x 16 in. Lay the lamb on the pastry, then fold the pastry up over the lamb to enclose it, sealing the edges together with a little beaten egg.

Transfer the pastry-wrapped lamb to a lightly dampened baking sheet, joins downward. Make 2 or 3 holes in the top of the parcel, about 20 mm (3/4 in) in diameter, to allow the steam to escape. Decorate around the holes with leaves made from pastry trimmings, attaching them with a little beaten egg. Lightly brush the pastry all over with cold water.

Carefully place some aluminium foil over the pastry leaves so that they do not get too brown in the oven, then bake in the oven for 10 minutes. Remove the foil, brush the pastry all over with beaten egg and bake for a further 10 minutes, until the pastry is puffed and golden. Serve hot.