Seal the jar, give it a good shake then put it in the cupboard.
You will need to shake it up every couple of weeks for the first couple of months. I find it's good to imagine it's someone who has upset you during the day to really get going! After a couple of months of periodic shaking, leave undisturbed until next winter.
Using a sieve, separate the gin from the the bits of sloe and sediment. Strain the gin to clear it.
Bottle and serve! Yum. It's nice to open it on a special occasion - Christmas, Mid-Winter Solstice, New Year's Eve - whatever!
You will find that the blackness of the berries stains the gin to a beautiful blush pink and the sugar gives a thickness to the consistency that gin doesn't have when it's served alone. The flavour is lush and almost medicinal - think Benylin!