
Gin is a neutral spirit redistilled with botanicals, and by law juniper has to lead. London Dry is the strictest grade: everything it tastes of has to come from the still, not from anything stirred in afterwards.
One London dry swaps for another one to one. The gin itself has no substitute: without juniper it is a different drink.
Old Tom gin
Deliberately sweetened, which London Dry may not be; swapping it in means taking about a barspoon of syrup out of the drink.
Genever
Gin’s Dutch ancestor on a malty grain base, so it sits closer to a light whiskey, and in a Martini it weighs the drink down and moves it from juniper toward grain.
The botanical bill and the still itself decide everything here, so two gins made to the same rules can taste quite different — the brand is not a detail in London Dry.

Aviation
London dry gin

Aviation Cocktail (Savoy recipe)
London dry gin

Basil Gimlet
London dry gin

Bee's Knees
London dry gin

Bee's Knees – IBA
London dry gin

Bijou Cocktail
London dry gin

Bramble
London dry gin

Breakfast Martini
London dry gin

Clover Club
London dry gin

Clover Club – IBA
London dry gin

Cosmopolitan Cocktail (1934 recipe)
London dry gin

Dry Martini 5:1
London dry gin

Dry Martini 7:1
London dry gin

French 75
London dry gin, Dry sparkling wine

French 75 – IBA
Brut Champagne, London dry gin

French 75 (1927 recipe)
Dry sparkling wine

Gibson Dry Martini
London dry gin

Gimlet
London dry gin

Gin and Tonic
London dry gin

Gin Basil Smash
London dry gin

Gin Basil Smash – IBA
London dry gin

Gin Basil Smash (low-calorie)
London dry gin

Hanky Panky
London dry gin, Rosso vermouth

Last Word
London dry gin