The present administrative governing body for London.
Established after a referendum in 1999.
Consists of the Mayor (not to be confused with the Lord Mayor of London - ie of the City of London) and a 25 member assembly, of which 14 are elected on a geographical/constituency basis and 11 on a London-wide basis.
Mayors of London
The Wikipedia page is [1].
The website is [2].
A research briefing here