The Greater London Authority Act 1999 (c. 29) is the Act of Parliament

Act of Parliament

An Act of Parliament is a statute enacted as primary legislation by a national or sub-national parliament. In the Republic of Ireland the term Act of the Oireachtas is used, and in the United States the term Act of Congress is used.In Commonwealth countries, the term is used both in a narrow...

 that established the Greater London Authority

Greater London Authority

The Greater London Authority is the top-tier administrative body for Greater London, England. It consists of a directly elected executive Mayor of London, currently Boris Johnson, and an elected 25-member London Assembly with scrutiny powers...

, the London Assembly

London Assembly

The London Assembly is an elected body, part of the Greater London Authority, that scrutinises the activities of the Mayor of London and has the power, with a two-thirds majority, to amend the mayor's annual budget. The assembly was established in 2000 and is headquartered at City Hall on the south...

 and the Mayor of London

Mayor of London

The Mayor of London is an elected politician who, along with the London Assembly of 25 members, is accountable for the strategic government of Greater London. Conservative Boris Johnson has held the position since 4 May 2008...

.

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

Metropolitan Police Authority

The Metropolitan Police Authority is the police authority responsible for supervising the Metropolitan Police Service, the police force for Greater London ....

 for the Metropolitan Police Service

Metropolitan Police Service

The Metropolitan Police Service is the territorial police force responsible for Greater London, excluding the "square mile" of the City of London which is the responsibility of the City of London Police...

, and consequently altered the borders of the Metropolitan Police District

Metropolitan Police District

The Metropolitan Police District is the police area which is policed by London's Metropolitan Police Service. It currently consists of Greater London, excluding the City of London.-History:...

 to be coterminous with Greater London

Greater London

Greater London is the top-level administrative division of England covering London. It was created in 1965 and spans the City of London, including Middle Temple and Inner Temple, and the 32 London boroughs. This territory is coterminate with the London Government Office Region and the London...

 (excluding the City

City of London

The City of London is a small area within Greater London, England. It is the historic core of London around which the modern conurbation grew and has held city status since time immemorial. The City’s boundaries have remained almost unchanged since the Middle Ages, and it is now only a tiny part of...

).

It was the longest Act to be passed by Parliament since 1935. http://www.citymayors.com/mayors/london_mayor.html