Preheat the oven to 170 C / Gas 3. Grease a 900ml ovenproof dish.
Put breadcrumbs, the 25g caster sugar and lemon rind into a basin. Toss lightly together to mix.
Pour milk into a saucepan. Add butter and heat gently until butter melts. (To microwave: Pour milk into a jug add butter and cook for 2 to 3 minutes until butter melts.)
Pour onto breadcrumb mixture, stir well and leave to stand for 30 minutes.
Beat in egg yolks. Spread into the prepared dish.
Bake until firm and set, about 30 minutes. (To microwave: cook uncovered on medium (50%) for 8 to 10 minutes until firm and set.) Remove from oven and spread with jam.
Fore the meringue: Put the egg whites in a clean dry bowl, beat until stiff and peaky. Gently fold in the 75g caster sugar with a large metal spoon.
Pile over pudding and then sprinkle with granulated sugar.
Return to oven and bake until the meringue is pale gold, about 30 minutes. (To microwave: cook uncovered on medium (50%) about 4 minutes until risen and set. Brown lightly under a hot grill; allow to stand for five minutes until serving.)