I love the name of this shop 'Sugar Sin', it sums up treats perfectly- sweet and a little bit wicked. It sells traditional British sweets, licorice comforts, chocolate raisins and mint humbugs. They're a little bit pricey but are good quality and beautifully presented. I can vouch for the chocolate and yoghurt coated nuts.
The interior of the shop is Willy Wonka territory, black and white stripy floors, pastel shelves and huge jars of pick and mix.
Sugar Sin is near to Covent Garden if you fancy dropping in, or alternatively you can shop online.