Info from Wikipedia
Fairfield Halls is an arts, entertainment and conference centre in Croydon, London, England, which opened in 1962 and contains a theatre and gallery, and a large concert hall regularly used for BBC television, radio and orchestral recordings.
The halls are built on the site of Croydon's historic "Fair Field", which hosted a well-known fair up until around 1860.
The building's concert hall has 1,801 seats (counting the choir stalls), the Ashcroft Theatre has 755, and the Arnhem Gallery is used for standing concerts of up to 400.