The name London refers to capital of England but the gin is not confined to the metro. In short the product is not restricted to geographical limits unlike champagne, scotch and tequila which are geo restricted. Champagne is produced in India but it cannot be called such since the production is not in the Champagne District of France. London Gin has thus become a standard and precedes other spirits of same style as far as yardstick of qualitative measure is concerned. It is the attributes that has accorded the product this status, the flavor, aroma, distillation process, blending and yes the consumption rate act as accreditation.
The spirit is named by its variant and not by its place of origin. London gin is a dry variety like Osel from Estonia and this liquor is vastly popular and trending whence consumed with Indian Tonic.