Use a strip of non-stick baking paper to line the base and short sides of a 1 kg (2 lb) loaf tin. Stretch each bacon rasher so it is half as long again, then butt close together to line the tin. Cut rashers in half to line the ends of the tin, and set aside a few rashers.
Heat the oil in a frying pan, add the onion and fry for 5 minutes until softened.
Mix the sausagemeat, chicken livers, chicken thighs, apple, nutmeg, nuts, breadcrumbs and sherry or brandy in a large bowl, then stir in the onions and seasoning. Spoon the mixture into the bacon-lined tin, pressing it down well.
Fold the ends of the bacon over the top, then cover the gaps with the reserved rashers. Cover with foil, stand the tin in a roasting tin and pour in hot water to come halfway up the sides. Cook in a preheated oven, 180°C (350°F), Gas Mark 4, for 1½ hours or until cooked when tested (see
Tip the water out of the roasting tin. Cool the terrine then cover top of the loaf tin with weights and chill overnight. Loosen the edges of the terrine, turn it out of the tin and peel away the lining paper. Cut into thick slices and serve with radishes.