Croydon: South London Jamatkhana
Three large houses have been used to form this building: part of these was formerly used as a private school. The Jamatkhana is, as I understand it, a centre for the study of Ismaili, which is a sect of Islam led by the Aga Khan. It is on Addiscombe Road, should you wish to visit it, just opposite the Sandilands tram stop.
Source: Geograph