Stir lemon juice, gin and simple syrup in a highball glass. Fill with ice cubes. Top up with soda water. Garnish with lemon.
The Tom Collins history is a little muddled. The name is believed to have its origins in John Collins, the head bartender at Limmer’s Hotel in London, whose similar signature drink was popular in the 1830s. The cocktail made it to New York in 1850 when a British officer taught it to the bartenders at the Clarendon Hotel. It was soon changed into Tom Collins and turned up in Jerry Thomas’ 1876 edition of “The Bartender’s Guide".