Put the apples, cider, 150 ml (¼ pint) of water, sugar and the rind of one of the lemons into a saucepan. Cover and simmer for 15 minutes until the apples are soft.
Meanwhile put the 4 tablespoons of water into a small bowl and sprinkle over the gelatine, making sure that all the powder is absorbed by the water. Set aside.
Add the gelatine to the hot apples and stir until completely dissolved. Purée the apple mixture in a blender or food processor until smooth, then pour into 6 tea cups. Allow to cool then chill for 4–5 hours until fully set.
When ready to serve, whip the cream until it forms soft peaks. Spoon over the jellies and sprinkle with the remaining lemon rind.