Fill a saucepan with cold water and place the eggs inside carefully. Bring to the boil over a high heat; once boiling start the egg timer for about 7 minutes for hard boiled. Drain and peel.
Remove the yolks and discard, this recipe only uses the whites. Chop the whites and place into a mixing bowl. Add the prawns, mayonnaise, horseradish, ketchup, salt, pepper and lemon juice and mix well.
Line a bowl or mould with greased cling film, and allow plenty of cling film overhang. Carefully spoon the mixture into the bowl mould and lightly press the mixture down with the back of a spoon to remove any air bubbles and compact the mixture. Place in the fridge to chill for 3 to 4 hours.
When ready to serve, carefully invert the bowl mould over a serving plate and gently pull on the cling film to release the set mixture; you should hear the mixture drop gently onto the plate. Remove the bowl and discard the cling film. Sprinkle with chopped fresh chives and serve immediately.