For a deeper flavour, cook the prawns from scratch. Heat 20g unsalted butter and 1 tbsp olive oil in a frying pan. Add 10 whole raw No.1 Madagascan tiger prawns with 1 chopped, fresh tomato, plus the celery salt, Tabasco and Worcestershire sauce as in the recipe above. Fry for a few minutes until the prawns turn pink and are cooked through. Once cool enough to handle, peel the prawns and mix with the ketchup, mayonnaise and lemon juice, adding the tomato from the pan.
Or if you're short of time, pick up a pack of Heston from Waitrose Bloody Mary Prawn Cocktail, ready to pile into a sliced bun with some crisp lettuce and celery.