The base spirit is distilled in a potstill then redistilled with 10 botanicals: juniper berries and elderflower, iris root from Italy, coriander from Morocco, angelica, sweet oranges and fresh whole lemons from Spain, liquorice root from India and whole vanilla beans from Madagascar.
The distillates are blended and diluted to drinking strength and then aged in new American oak barrels for a short period. This aging in wood is done to create an authentic flavour profile.
Bottles were pretty rare and expensive in the 18th century so it is most likely that Old Tom gin was shipped, stored and served from a barrel and as such must have had some wood influence in the character.
The nose is spicy and complex with cardamom and juniper softened by vanilla notes. The flavour is ever so slightly sweet with earthy juniper and vanilla and wood spices.
Old Tom Gin is great in a Martinez of Negroni cocktail.