London mayoral election: The contenders

Twelve candidates are hoping to succeed Boris Johnson as mayor of London in the election on 5 May.

As well as representatives of the Conservative, Labour, Green, Liberal Democrat and UK Independence Parties, the list includes the former MP George Galloway and the son of a Polish aristocrat.

Conservatives

Zac Goldsmith, son of the late billionaire Sir James Goldsmith, was educated at Eton and Cambridge Centre for Sixth-form Studies before becoming editor of the Ecologist magazine. He was elected MP for Richmond Park in 2010 and increased his majority in 2015 - a constituency which had previously been a Lib Dem stronghold. He is known for his involvement in environmental issues, particularly his vocal opposition to Heathrow expansion. In 2012 he vowed to stand down as an MP if the government backed it. He has also been a leading campaigner on introducing greater powers for constituents to recall their MPs - which the government legislated for in 2014, although not entirely to Mr Goldsmith's satisfaction.

In that spirit, he held a referendum in his constituency to seek voters' permission to stand for mayor. They duly gave it, and he pledged to fight for a "safer, greener, happier, more prosperous, united city". Mr Goldsmith is hoping to continue in the tradition of Boris Johnson, pledging not to raise the mayor-controlled element of council tax at the same time as giving Transport for London the funding it says it needs to upgrade the Tube. He says he would ensure 50,000 new homes are being built every year in London by 2020 but has also vowed to protect greenbelt land.

Labour

Sadiq Khan, son of a bus driver, grew up on a south London housing estate. He attended a local comprehensive school before going to university and training as a lawyer and went on to become a human rights solicitor, representing claims of racism against the Met and helping to overturn a ban on Nation of Islam leader Louis Farrakhan entering the UK. Shortly after being elected MP for Tooting in 2005 he became parliamentary private secretary to then Commons leader Jack Straw. He became one of the first British Muslims to sit on the frontbench when he took up a ministerial role in the Department for Communities and Local Government and later the Department for Transport. In opposition, he became shadow justice secretary and was involved in the campaign against coalition reforms to legal aid.

Announcing his decision to run as mayor, he called Mr Johnson a "red-carpet mayor" whereas he would "fight for all Londoners". Like his predecessor as Labour candidate, Ken Livingstone, he is promising to freeze Transport for London fares for four years. He has already clashed several times with Mr Goldsmith on the best way to improve the housing supply for London. His idea is to build a minimum of 80,000 homes a year and specify that 50% of new housing built on public land must be designated as affordable.

Greens

Sian Berry is a former principal speaker for her party, and the only Green councillor on the Labour-run borough of Camden. She also ran for City Hall in 2008. She worked in medical communications before becoming involved in politics, and was involved in local campaign group Alliance Against Urban 4x4s. In 2012, she helped organise the "Sack Boris" slogan with the Transport Salaried Staffs Association union, which was used on leaflets and specially printed Oyster card holders.

She also spent several years working for the charity the Campaign for Better Transport. In May, the Green Party will hope to match its 2012 record, when their then candidate Jenny Jones beat the Lib Dems into third place. Sian Berry has said that as mayor she would get rid of City Airport, establish a renters' union and introduce "flat fares" across London travel zones.

Lib Dems

Caroline Pidgeon is the only candidate currently sitting at City Hall, where she has been an Assembly Member since 2008. She is the party's leader at the London Assembly, and deputy chair of the London Assembly's Transport Committee and Police and Crime Committee.

Some clues to the uphill battle she faces were provided in her selection, when the only other shortlisted candidate withdrew his name in favour of taking a job with the police. Launching her campaign she said she wanted to tackle the barriers that make London "a city that serves the few, not the many". Her flagship policies include half-price fares for journeys starting before 07:30 and scrapping the Garden Bridge.

UKIP

Peter Whittle, previously UKIP's culture spokesman, contested the seat of Eltham in the general election. He has written about what he argues is a shortage of right-leaning voices in the arts and has spoken extensively about the effects of migration from the EU on the capital, particularly in relation to housing.

He has also said he would support the use of stop and search to help tackle youth crime, an area which has been the focus of some tension between the Met and the government recently. UKIP placed sixth in the 2012 mayoral race but will hope to build on a better performance at the 2015 general election, when they came third in the popular vote.

Read more about the other mayoral and London Assembly candidates.