SW4 Gin was made with the express purpose of creating a traditional style gin that would match perfectly with tonic. It is the creation of Charles Maxwell, who uses a 12 botanical recipe (juniper, lemon zest, savory, orange zest, coriander, orris root, cinnamon, cassia, liquorice root, almonds, angelica, and nutmeg) to make a gin in the 19th century style. From the website: "The older style gins being made to show at their best when mixed with water, ginger beer and most especially tonic, that eponymous drink of the British Empire." The spirit is from a base of wheat and barley, then macerated (that is, soaked) with the botanicals for 12 hours prior to distilling.
While the gin is owned and overseen by Maxwell of Park Place Drinks, it is produced at Thames Distillers, which we have listed here as the producer.