Set aside a dozen berries for a garnish. Put the rest of the berries in a saucepan with sugar and strained lemon juice. Set over low heat, cover and simmer gently for 10 minutes.( as the fruit heats juice will form). Put water in a bowl and sprinkle gelatin over and stir.Set aside to soak for 5 minutes.

Take fruit off heat, add gelatin and stir until dissolved. Pass fruit through a sieve to make a puree. Rub through as much fruit as possible. Discard pips left in the sieve. Set puree aside until cooled and it begins to thicken.

Meanwhile, beat egg whites stiffly and the cream lightly. Fold both with the fruit puree until evenly blended. Put in a serving dish and chill until firm. Decorate with whipped cream and reserved blackberries. Serves 8 to 10 people.