A cocktail consisting of 45 ml (1½ fl oz) London Dry gin, 45 ml (1½ fl oz) Noilly Prat, 15 ml (½ fl oz) Rose’s lime juice or 90 ml (3 fl oz) fresh lime or grapefruit juice, Perrier, twist of cucumber peel. Shake the liquor and fruit juice very thoroughly with ice cubes and strain into ballon wine glass over 2-3 ice cubes. Top up with Perrier. Decorate with peel.