Heat the grill to medium-high. In a small bowl mix the prawns, smoked paprika, mayonnaise, lemon juice, capers and shallot. Season with salt and pepper to taste.
Put 4 of the slices of bread on a baking sheet and grill for 1-2 minutes, flip and grill for another 1-2 minutes. Remove from the oven and top them with the prawn mixture, tomato slices and the grated cheddar.
Add the other 4 slices of bread to the tray and put back under the grill for 4-5 minutes, flipping the slices without topping half way through. Remove from the oven when the cheese is melted and browned and the other slices of bread are toasted to your liking. Top each prawn slice with a plain piece of toast and serve.
Nutrition information is an estimate and will vary depending on the exact ingredients used.