The Society of Antiquaries of London (SAL) is a learned society "charged by its Royal Charter of 1751 with 'the encouragement, advancement and furtherance of the study and knowledge of the antiquities and history of this and other countries'." It is based at Burlington House, Piccadilly, London (a building owned by the UK government), and is a registered charity.
More information on the Wikipedia page [1]
The website is [2].