Place 9 bar spoons of bilberries into a sling glass and muddle
Fill the sling glass to the top with crushed ice
Pour in 0.5 oz of lemon juice, 0.35 oz of blackcurrant syrup, 0.5 oz of sugar syrup and 1.25 oz of gin
Top up with Sprite and stir gently
Top up with crushed ice
Garnish with a lime wheel and a mint sprig