Blitz the biscuits in a food processor until beginning to turn to crumbs, then add the butter and whiz again to make the mixture clump.Press this mixture into a 20cm / 8 inch springform tin; press a little up the sides to form a slight ridge.Beat together the cream cheese, icing sugar, vanilla extract and lemon juice in a bowl until smooth.Lightly whip the double cream, and then fold it into the cream cheese mixture.Spoon the cheesecake filling on top of the biscuit base and smooth with a spatula. Put it in the fridge for 3 hours or overnight.When you are ready to serve the cheesecake, unmould it and spread the black cherry over the top.