Les Ambassadeurs Club gained a reputation as one of London's most exclusive and distinguished gaming and dining clubs with a membership drawn from the world's aristocracy, diplomats, heads of state, chiefs of commerce and celebrities. When John Mills relocated Les Ambassadeurs Club to No. 5 Hamilton Place in 1950, the club returned to the limelight and resumed its fascinating history. Over the coming years, Les Ambassadeurs Club was home to various ventures, including The Milroy Nightclub, The Garrison Club and Le Cercle, one of London's first gaming clubs complete with French croupiers, Paris-made chips and correct kidney-shape tables. Le Cercle was something of an innovation and as such, when it opened in May 1961 (to members of Les Ambassadeurs only), it attracted the notice of The Times newspaper, which was most impressed by its "high standard of professionalism and sophistication".
John Mills ran Les Ambassadeurs Club until 1981, when it was purchased by casino group London Clubs International (LCI) part of Caesars Entertainment Corporation and in 2006 by Bluestream Holdings Limited. Since the early 1990s, Les Ambassadeurs Club has established itself as one of the most exclusive casinos and sought after memberships in the world. In 2016, Landing International Development Limited purchased Les Ambassadeurs Club marking the most recent phase in No. 5 Hamilton Place history.