Place the apricots in a saucepan and just cover with boiling water. Cover and leave for 2 hours to soak. Simmer over gentle heat for 40 minutes until tender. Keep the pan covered and simmer very gently; if the water is allowed to evaporate too quickly the apricots may burn. Check the pan occasionally and add more water if necessary. Meanwhile, measure the cold water into a small basin and sprinkle in the gelatine. Set aside to soak.
When the apricots are soft, draw the pan off the heat and stir in the lemon juice and half the sugar. Then pass the apricots and the juices in the pan through a sieve to make a purée. Discard any pieces of skin left in the sieve. Return the apricot purée to the saucepan and add the soaked gelatine. Stir over very low heat just long enough to dissolve the gelatine. Pour into a mixing basin.
Measure the milk into a saucepan and bring almost to the boil. Blend the egg yolks and remaining sugar in a basin, stir in the hot milk and blend well. Pour this custard into the milk pan and stir over low heat for 1–2 minutes, but do not allow to boil.
Combine the hot custard with the fruit purée and set aside until cold. When beginning to thicken, fold in the lightly whipped cream. Pour into a