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.