Preheat the oven to 170°C / Gas Mark 3-4. Prepare a 20cm spring-form tin by lightly greasing and lining the base with a disc of grease proof paper.
Make the biscuit base by mixing together the crushed digestives, melted butter and 2 tbsp Whitworths Caster Sugar. Press into the prepared 20cm spring-form tin. Place in the fridge to chill for 1 hour.
In a large bowl, beat the cream cheese, Whitworths Caster Sugar, soured cream, vanilla extract and eggs until well-mixed. Fill the kettle and boil.
Take a large roasting tin and sit the cheesecake tin inside, pour the mixture onto the biscuit base.
Place the roasting tin in the oven and carefully pour the boiling water into the roasting tin so the water comes half-way up the outside of the cheesecake tin.
Bake for 50 minutes until firm, check the cheesecake after 30 minutes, if the top is browning too much, loosely cover with foil.
Take the cheesecake out of the oven and allow to cool before putting in the fridge for 2-3 hours to chill completely.