Sort through the blackberries and remove any stalks, leaves or mouldy berries. If using wild berries, soak them in cold salted water for 10 minutes to shake out any bugs, then rinse and drain.

Put the berries in a large clean jar and lightly crush them with the end of a rolling pin.

Add the sugar, lemon peel if using, and the vodka. Seal and shake well.

Shake daily for a week, then weekly. Keep the jar in a cool, dark place.

After 4 to 6 weeks, strain through a sieve lined with muslin. Don't press the fruit too hard or it will cloud.

Bottle, label and store somewhere cool and dark.