Greater London Council (GLC) Coat-of-Arms - Albert Embankment, London, UK - Coats of Arms on Waymarking.com

The plaque, showing the coat-of-arms, are located over the two pedestrian entrance doors one located at each end of the building.

The Heraldry of the World website tells us:

The arms were granted on October 5, 1966 and are a combination of those of London (the barry wavy base)and Middlesex (the Saxon crown ) County Councils.

Official blazon: Barry wavy Argent and Azure on a Chief Gules a Saxon Crown Or.

The Manchester History website tells us about the building:

The large site is in two sections on either side of Lambeth High Street. The eight storey building on the Albert Embankment is built using Portland stone and light coloured brick. On the ground floor are both the Lambeth and the Lambeth River Fire Stations, together with a gym. For the first floor the architects designed living quarters and recreation rooms for on-duty fire crews together with a London-wide control room. The upper stories also contained the main administrative offices for the brigade and numerous flats for fire officers. Behind this building is a large drill yard complete with a 100ft drill tower with built-in hose drying facilities and a separate bandstand!

Wikipedia tells us about the GLC:

The Greater London Council (GLC) was the top-tier local government administrative body for Greater London from 1965 to 1986. It replaced the earlier London County Council (LCC) which had covered a much smaller area. The GLC was dissolved in 1986 by the Local Government Act 1985 and its powers were devolved to the London boroughs and other entities.

The GLC was established by the London Government Act 1963, which sought to create a new body covering all of London rather than just the inner part of the conurbation, additionally including and empowering newly created London boroughs within the overall administrative structure.

In 1957 a Royal Commission on Local Government in Greater London had been set up under Sir Edwin Herbert, and this reported in 1960, recommending the creation of 52 new London boroughs as the basis for local government. It further recommended that the LCC be replaced by a weaker strategic authority, with responsibility for public transport, road schemes, housing development and regeneration. Most of the Commission’s recommendations were accepted, but the number of new boroughs was reduced to 32. Greater London covered the whole County of London and most of Middlesex, plus parts of Essex, Kent and Surrey, a small part of Hertfordshire and the County Boroughs of Croydon (Surrey) and East and West Ham (both in Essex), all of which had been independent of county council control since 1889.

Some areas on the boundaries of the area recommended by the Herbert Commission, fearing increased local taxation, fought successfully not to come under the new Greater London Council, notably the urban districts of Chigwell in Essex; and Sunbury-on-Thames, Staines and Potters Bar in Middlesex. Other areas recommended for inclusion that were never part of Greater London included Epsom and Ewell, Caterham and Warlingham, Esher, and Weybridge.

GLC councillors elected for areas within the former County of London became ex officio members of the new Inner London Education Authority, which took over the LCC responsibility for education; in Outer London, which was the rest of Greater London, the various London boroughs each became a local education authority, akin to a county council or county borough in the rest of England.