I've seen it in drink shops, but it easy to make yourself and its just the right time of year.
Just pick sloes - the big blue black berries that look like olives - on the thorny blackthorn bushes in old hedgrows, put them in a bottle of gin, and store for a few months.
When my Mum makes sloe gin, I always get mugged with the labourious bit, as she insists every sloe is pricked with a pin!! Mum has got some that is about 6 years old and it has become a wonderful liquer. Normally I hate gin!
1lb Sloes, 4oz caster sugar, 1 bottle of Gin.
Prick the sloes with a toothpick then put everything in a Kilner jar. Leave the jar for at least two months but shake it up every couple of days. After two months or so strain it through two layers of muslin (or a filter) and bottle it, a dessertspoonfull of glycerine may be added at this stage to make it smoother. The Sloe gin is best if left for a while before drinking. You can use the same method with Damsons to make Damson Gin.