Boris Johnson

Boris Johnson, London Mayor, delivers his speech at the Conservative party conference in Birmingham.

Charlie Bibby/FT

Boris Johnson, London Mayor, delivers his speech at the Conservative party conference in Birmingham.

Prime Minster, David Cameron, laughs as Boris Johnson, London Mayor, delives his speech at the Conservative party conference in Birmingham this afternoon.

Charlie Bibby/FT

Prime Minster, David Cameron, laughs as Boris Johnson, London Mayor, delivers his speech at the Conservative party conference in Birmingham this afternoon. 

British Prime Minister Prime Minister Da...British Prime Minister Prime Minister David Cameron (L) and Mayor of London Boris Johnson wait for a train at Newark station in central England on May 21, 2014, following a visit to the town were they campaigned ahead of the Newark by-election which is due to be held on June 5. Voters also go to the polls in Britain Thursday May 22, 2014, for local council elections in England and Northern Ireland and also for European elections in England, Wales, Scotland and Northern Ireland. AFP PHOTO / STEFAN ROUUSEAU/POOLSTEFAN ROUSSEAU/AFP/Getty Images

Stefan Rousseau/Getty

British prime minister David Cameron and London mayor Boris Johnson wait for a train at Newark station in central England following a visit to the town were they campaigned ahead of the Newark by-election which is to be held on June 5

Britain's Prime Minister David Cameron (...Britain's Prime Minister David Cameron (4th L) and Mayor of London Boris Johnson (3rd R) are pictured during a visit to a Crossrail construction site underneath Tottenham Court Road in central London, on January 16, 2014. The Crossrail project, which is expected to be completed in 2018, will link Berkshire, west of London with Essex, east of London.

Ben Stansall/AFP

David Cameron, UK prime minister, and mayor of London Boris Johnson visit a Crossrail construction site underneath Tottenham Court Road in central London. Crossrail, which is expected to start running in 2018, will link Berkshire, west of London, with Essex, east of London. Mr Cameron is pictured fourth from left, Mr Johnson third from the right 

Mayor of London, Boris Johnson firing the salute from the Honourable Artillery Company’s 105mm light gun to mark the launch of London Poppy Day at Armoury House, home of the Honourable Artillery Company (HAC), London.,

Cpl Steve Blake/MoD//Crown Copyright/EPA

Mayor of London, Boris Johnson firing the salute from the Honourable Artillery Company’s 105mm light gun to mark the launch of London Poppy Day at Armoury House, home of the Honourable Artillery Company (HAC), London.,

Mayor of London Boris Johnson and Chancellor of the Exchequer George Osborne meet students at Peking University in Beijing where they addressed and held a Q&A with staff and students.

Stefan Rousseau/PA

Boris Johnson, mayor of London, and George Osborne, chancellor of the UK exchequer, hold a Q&A at Peking University in Beijing

An Alternative View Of The Conservative Party Annual Conference...MANCHESTER, ENGLAND - OCTOBER 01:  (EDITOR'S NOTE: Image was processed using digital filters. Colour version not available) Boris Johnson, the Mayor of London, delivers his speech in the Main Hall of Manchester Central on the third day of the Conservative Party Conference on October 1, 2013 in Manchester, England. David Cameron has unveiled a Government pilot scheme for GP surgeries to open from 8am until 8pm seven days, backed by 50 million GBP of funding.

Christopher Furlong/Getty

Boris Johnson, Mayor of London, delivers a speech on Wednesday on the third day of the Conservative Party’s annual conference in Manchester, UK.

Launch of the Mayors Challenge...(left to right) Hanna Gronkiewicz-Waltz the mayor of Warsaw, Boris Johnson the Mayor of London, Michael Bloomberg the Mayor of New York and Matteo Renzi the Mayor of Florence at the launch of the Mayors Challenge in Europe at City Hall in London. PRESS ASSOCIATION Photo. Picture date: Tuesday September 24, 2013. The competition invites leaders of European cities to enter with prizes of 5 million Euros for the grand winner. Photo credit should read: Philip Toscano/PA Wire

Philip Toscano/PA

Four mayors – from left, Hanna Gronkiewicz-Waltz of Warsaw, Boris Johnson of London, Michael Bloomberg of New York and Matteo Renzi of Florence – at the launch of the Mayors Challenge in Europe at London’s City Hall. The competition invites European cities to compete for €9m in prizes for ideas to improve urban life.