The story
Founded by Herbert John Buckmaster.1
During the First World War, Captain Herbert John Buckmaster (1881-1966) of the Royal Horse Guards and some of his colleagues agreed that after the war it would be good to establish a gentlemen's club that was somewhat less stuffy than existing clubs. They particularly wanted a club with an American cocktail bar, something then beyond the pale for most traditional gentlemen's clubs.
The club was established in June 1919
and its American Bar was a focal point. American members were welcome although treated separately from a constitutional standpoint. The club for many years kept its tradition of sourcing members from the Household Cavalry regiments although its membership is now drawn from many walks of life and is renowned for its exuberance and the youth of its membership.
The Club is probably best known for seeing the creation of the Buck's Fizz cocktail in 1921 by its first bartender, Mr McGarry (Barman from 1919 to 1941, sometimes "Malachy McGarry" or "Pat McGarry", or spelled "MacGarry", he is also usually credited with creating the Sidecar cocktail).
It receives three mentions in the stories of P. G. Wodehouse; Wodehouse modelled his fictional Drones Club after Buck's Club and the Bachelors' Club, even naming his club's barman "McGarry" too.
From Wikipedia’s article on Buck's Club, shared under CC BY-SA 4.0.4