From the Wikipedia page 
The London Metropolitan Archives (LMA) are the main archives for the Greater London area. Established in 1997, having previously been known as the Greater London Record Office, they are financed by the City of London Corporation.
They are an amalgamation of four separate archives: The London County Record Office, The London County Council Members Library and The Middlesex County Record Office, which came together to form the Greater London Record Office and History Library (GLRO) in 1965. The Greater London Record Office then became the London Metropolitan Archives in 1997 and has since merged with the former Corporation of London Record Office (CLRO)
Based at 40 Northampton Road, Clerkenwell, London, they are close to the Society of Genealogists. The archives attract over 30,000 visitors a year and deal with a similar number of written enquiries. The LMA's extensive holdings amount to over 72 miles of records of local, regional and national importance. With the earliest record dating from 1067, the archive charts the development of the capital into a modern day major world city.
The LMA website is