Cut peaches in half and discard the pits. Chop flesh into chunky pieces. Remove rind of lemons (you need a teaspoonful of rind only). Squeeze juice from lemons.
Cmbine peaches, apples, lemon rind and juice in a large saucepan. Bring to a boil, then simmer covered for approximately half an hour or until fruits turn soft. Add in sugar and stir without boiling until sugar is dissolved.
Bring to a boil, then boil uncovered without stirring for another half an hour or until the mixture reduces to a jelly-like consistency. Pour jam into hot sterilised jars. Seal when cold.
To test if jam has jelled, drop a teaspoon of the mixture onto a saucer which has been chilled in the freezer for a few minutes. The jam should be a firm mass on the saucer.