To make the jelly, put the gelatine in a small bowl and cover with water. Leave to soak. Meanwhile, tip the sugar, lemon zest and juice and 400ml water into a pan and simmer, stirring occasionally, until the sugar has dissolved. Add the raspberries and bring to the boil. Reduce to a gentle simmer and cook for 5 mins, or until the raspberries have broken down. Pour the mixture through a sieve into a jug. Squeeze any excess water out of the gelatine and stir through the raspberry mixture. Pour into the base of a large trifle bowl and chill for at least 5 hrs, or overnight.

To make the custard, heat the milk in a pan with the vanilla pod until steaming, then remove from the heat and set aside. Whisk the sugar, cornflour and egg yolks together in a bowl. Remove the vanilla and gradually pour the hot milk into the egg mixture, whisking constantly until well combined. Return to the pan and gently stir over a low heat until the custard has thickened. Stir in the clotted cream, pour into a bowl and cover the surface with a piece of baking parchment to prevent a skin forming. Leave to cool, then put in the fridge to chill until cold.

Put the frozen raspberries and jam in a small pan and cook for 5 mins until the raspberries have softened a little but are still holding their shape. Leave to cool. Whisk the cream with the icing sugar in a large bowl until it reaches a soft dropping consistency.

Arrange the cake pieces over the set jelly. Crush most of the biscuits, reserving some whole, and scatter over the cake layer. Whisk the custard to loosen, then pour over the biscuit layer. Top with the raspberry compote, pushing the whole biscuits into it around the edges of the bowl. Spoon over the whipped cream, then decorate with the sprinkles and cherries, if you like. Will keep in the fridge for up to three days.