Pick over the prawns and shred the lettuce leaves – the easiest way is to roll the leaves up together and then shred them across finely. Shake the lettuce to separate the pieces and place in a polythene bag with a sprinkling of water to keep fresh in the refrigerator.
Combine together the mayonnaise, tomato ketchup, cream and Worcestershire sauce for the dressing. Add a good squeeze of lemon juice – check flavour for sharpness. Add the prawns and set aside.
When ready to serve, place a little shredded lettuce in the base of six individual glasses. Spoon the sauce and prawns on top. Garnish with a sprinkling of paprika and serve with thinly sliced brown bread and butter.