Preheat the oven to 180º C. Grease and line a 20cm round cake tin.
Cream the butter, castor sugar and vanilla.
Add the eggs, one at a time, beating well between each addition.
Sift together the flour, baking powder and salt.
Add the flour and milk in stages and whisk until all the flour is incorporated.
Spoon the batter into the tin and bake for 30-32 minutes.
Rest in the tin for 10 minutes before turning out on a wire rack to cool completely.
To assemble, slice the cake in half horizontally and spread with berry preserve.
Pour the jelly into the trifle bowl and add the mixed berries. Chill until set.
Place the cake carefully on top of the jelly and drizzle with sherry.
Pour the custard over, followed by the whipped cream.
Decorate with raspberries and dainty meringues. Dust with icing sugar and serve.