Greater London Authority Act 1999

The Greater London Authority Act 1999 (c. 29) is the Act of Parliament that established the Greater London Authority, the London Assembly and the Mayor of London.

The Act was brought in after a referendum, held under the Greater London Authority (Referendum) Act 1998, had resulted in a 'yes' vote. Apart from the main provisions creating the authority and transferring powers to it, it also created a Metropolitan Police Authority for the Metropolitan Police Service, and consequently altered the borders of the Metropolitan Police District to be coterminous with Greater London (excluding the City).

It was the longest Act to be passed by Parliament since 1935.