Preheat the oven to 170C/325F/gas Mark 3. Line the bottom of a 20cm spring form or loose bottom cake tin with greaseproof paper. (Alternatively bake the cheesecake in a pie dish, without lining, so it is ready to serve straight from the dish).
To make the base mix the melted butter into the crushed biscuits and press into the base and sides of the tin with the back of a spoon. Refrigerate while you prepare the ﬁlling.
Mix both the cheeses, the sugar, eggs, vanilla, lemon zest and juice, and beat until well blended. Spoon into the prepared base and smooth over the top with a knife. Bake in the oven for one hour.
After an hour switch the oven oﬀ, leaving the cheesecake inside for a further two hours.
After two hours remove the cheesecake from the oven and allow to cool completely. Run a knife around the sides, then remove the outer spring form tin. Turn the cheesecake out onto a plate so that you can remove the bottom of the tin and the paper. Place the serving plate over the cheesecake base and invert so that it is ready to decorate.
Place the cranberries in a saucepan with the water and sugar and boil gently heat for 5-10 mins until the berries start to burst. Add the marmalade. Bring back to the boil, stirring occasionally to mix well. Allow the topping to cool completely, then spoon over the cheesecake. Refrigerate until ready to serve.