Turns out that the bartenders drink is pretty individual to whoever makes it.
Here’s 10 different top London bartenders proportions (in ml) to make that very classic rum cocktail.
Ingredients are Rum-Lime-Sugar (Simple syrup)
50-20-10
50-15-20
60-25-25
50-25-10
60-30-10 (2:1)
60-20-12.5
60-20-10
50-12.5-6
60-25-15 (gomme syrup + egg white)
60-20-15 (2:1)