Bring a pan of water to the boil, and with a sharp knife score the peaches around the groove that runs around from the stalk to the tip, then again at right angles so the skin is marked in quarters. Drop the peaches into the boiling water for a minute, then remove and peel off the skin. Chop all the flesh away from the pips and discard the skin (reserve the pips).
Peel the apples and grate them, discarding the core and pips. Place the grated apple in a pan with 300ml/½ pint of water, bring to the boil and then cook for 10 minutes, or until the water has almost evaporated.
Add the peach flesh and the stones and cook for a further 10-15 minutes, or until the peach pieces fall apart and the mixture is thick. Pick the stones out with a spoon and discard them.
Add the maple syrup, sugar and lemon juice, bring to a boil then cook until the mixture reaches 105C/220C on a sugar thermometer. Stir frequently to stop it catching on the bottom.
Leave to cool for a few minutes, spoon into hot, clean jars and seal immediately.