Lemon marmalade and Granny Smith crumble tart

I mix quickly into crumbs. I form a block, wrap in cling film and refrigerate for at least half an hour.I peel and finely dice apples into a bowl.I mix with the 3 tablespoons brown sugar and a tablespoon of cornflour.I combine equal weights of flour, butter and sugar into fairly large crumble pieces and refrigerate while rolling the pastry.I roll chilled pastry into the tin, leave baking parchment underneath and prick with a fork.I spread marmalade on the base.I add apples and press lightly.I spread crumble evenly over them.I bake at 180°C for 35/40 minutes until golden and cool before removing from the tin.