Grab a cocktail shaker and fill it with ice. Pour 60ml of Tanqueray, 30ml of lemon juice and 15ml of simple syrup. Shake until the contents are well combined.
Using a cocktail strainer, strain the mixture into a glass filled with crushed ice. Pour 22.5ml of crème de mûre into the mix.
Garnish the drink with a lemon wheel and a blackberry.
