Quarter the plums and discard the stones. Put the plums into a cooled dry 2 litre sterilised jar. Add the sugar and spices and stir together.
Add the vodka and brandy. Seal the jar and rock in gently.
Leave to macerate in a dark place at room temperature for up to 2 months, gently shaking the mixture daily for one week to dissolve the sugar then once a week thereafter.
After this time strain through a fine meshed sieve, pressing with the back of a spoon and discarding any pulp.
Restrain through a muslin lined fine meshed sieve to make the liqueur even clearer, then return to you cleaned and sterilised jar and store for a further month.
Strain a third time using a double muslin lined fine meshed sieve. Pour into cooled, dry sterilised bottles and seal.