In 2004 Conway Hall celebrated it’s 75th anniversary. South Place Ethical Society (now Conway Hall Ethical Society) for who the Hall was purpose built in 1929, celebrated with an evening of talks, tours, music and exhibitions. 
The American Ethical Union even sent over a proclamation to mark the event.
Artists impression of Conway Hall.
Image © Conway Hall Ethical Society
Humanist Library and Archives reference: SPES/6