Put the vinegar in the top part of a double boiler. If you don’t have one, sit a bowl with a lid over a pan of gently simmering water. You should find one of your saucepan lids to fit.
Add the ginger, cloves, cinnamon stick, allspice berries, bay leaves and peppercorns. Put over a low heat for 2 hours.
Pass through a muslin-lined sieve and you are ready to start pickling.