Start this recipe by making up the jelly. Place the defrosted strawberries and any juices into the base of a glass trifle stand. Pour over the jelly and place into the fridge to set. When ready, slice up the jam Swiss roll and lay on top of the jelly. Soak with the sherry or the liqueur of your choice. Next, make the custard by heating together the cream, milk and vanilla until almost boiling. Next, place the egg yolks, corn flour and sugar into a large bowl and whisk together for 1 minute. Pour over the almost boiling milk mixture, whisk and place back into the pan. Continue to cook and whisk until the custard thickens and boils. Immediately pour over the sponge and spread out. Allow to cool in the fridge till firm. When ready, whip together the 2 pots double cream, vanilla and icing sugar to stiff peaks and spread over the custard. Decorate the top with the fresh berries and serve.