FACTBOX-Guide to May 1 elections

LONDON (Reuters) - Voters in London go to the polls on May 1 to elect the capital's mayor.

Here is a guide to polling day:

What are people voting for?

- Voters will choose the next Mayor of London. The mayor makes London-wide policies on transport, planning, policing, culture, the environment and economic development.

- Voters will also elect members of the London Assembly. The assembly examines the mayor's plans and decisions and reviews his or her annual budget.

Why does everyone get four votes and three ballot papers?

- Voters cast four votes: Their first choice for Mayor of London; their second choice of Mayor; a vote for an assembly member in their constituency and a vote for a party or independent candidate to stand as one of 11 London-wide assembly members.

How is the mayor elected?

- If one candidate wins more than 50 percent of the first choice votes, he or she will be the winner.

- However, if no one wins half the vote, the two candidates with the most first choice votes will contest a second round.

- The second choice votes from the defeated candidates are counted. Votes for the top two candidates are added to their totals.

- The winner is the candidate with the highest combined total of first and second choice votes.

Who can vote?

- Voters must be 18 or over, live in London and be a British, European Union or Commonwealth citizen.

- People must be registered to vote.

How can they vote?

- People can vote in person at polling stations from 7 a.m. to 10 p.m. on Thursday, May 1.

- Anyone can vote by post. They must first ask their local borough council for a postal vote form.

- People can vote by proxy if they are out of London, disabled or blind. Voters should contact their local council to nominate a proxy voter.

When will the result be announced?

- Electronic counting will start at three count centres at 9 a.m. on May 2.

- The count is expected to take 12 hours.

- The centres are at Alexandra Palace, north London, the Olympia exhibition centre in west London and the ExCeL centre in Docklands.

(Source: London Elects)