h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I know that (as the entry asserts) a slice of lemon is the traditional garnish for a G&T. But I assure you that, once you've tried it with a slice of fresh *lime* instead, you'll never want to drink it any other way.

I agree. I spent many years in pubs, and at one point had some training from the Gordons company, one of the biggest Gin manufactors.
Now, this is the way they reckon to pour the perfect Gin&Tonic.
1)Get a long, tall, cold glass. Know as a Slim Jim.
2)Fill the glass with ice cubes, not just a couple in the bottom, but fill it to the brim!
3)Pour in a generous measure of gin, a double at least
4)Top up to just below the brim with cold tonic water. The tonic will settle the ice cubes down a bit further in the glass.
5)Take a segment of lime, not a slice, and squeeze it gently into the glass, then wipe the lime segment around the brim before dropping it into the glasss.
6)Stir the drink with a swizzle stick.
7)Drink
8)Repeat steps 1 - 7

You are correcct, Sir!!!

It's just the perfect drink for a summers afternoon and evening. In fact, the sun is shining now....