The Royal Over-Seas League, usually abbreviated to ROSL, is a London-based, not-for-profit membership organisation founded in 1910 to promote international friendship and cultural exchange. It operates a Grade I listed clubhouse in St James’s, with a strong arts, music, and public affairs programme, and it was granted a Royal Charter in 1922.
ROSL describes itself as a non-partisan organisation created by Sir Evelyn Wrench to foster international collaboration, culture, and conversation. It is also a Commonwealth-focused body with membership open to Commonwealth citizens, and affiliated membership available to some others.
Its London clubhouse includes dining, bedrooms, event spaces, and a garden overlooking Green Park. The organisation also runs concerts, art exhibitions, lectures, and other events, including a long-running Public Affairs series.
 
Interesting facts...
Admiral Edward Vernon (1684–1757), nicknamed “Old Grog” for his grogram cloak, diluted Royal Navy rum rations with water in 1740 to curb drunkenness—creating “grog,” a staple until 1970. His Porto Bello victory (1739) brought fame, but sailors grumbled at the mix.