What are directly elected mayors?

The idea of directly elected mayors was brought forward in 2000, in the Local Government Bill. It allowed for mayors to be introduced if the idea was supported in a local referendum.

The idea was that powerful US-style mayors, might help reinvigorate local elections, where turnout can be extremely poor, and would mean electors would have someone to hold to account over local services.

But critics say it concentrates too much power in one person's hands.

They have similar powers to those of the council leader and its executive committee in other local authorities - including setting the annual budget, set policy for things like libraries and community care, and to appoint councillors to a cabinet and delegate powers to them.

Who has them?

Thirteen English districts now have directly elected mayors - including London, although mayor Ken Livingstone has different powers to his regional counterparts.

The other twelve are: Bedford, Doncaster, Hackney, Hartlepool, Lewisham, Mansfield, Middlesbrough, Newham, North Tyneside, Stoke-on-Trent, Torbay and Watford.

Four are held by independents, including Stuart "H'Angus the Monkey" Drummond - a former football club mascot - in Hartlepool, which is not up for grabs this year.

There have been 34 referendums on whether to have elected mayors in England - of which 22 have been rejected. Usually the council requests a referendum, although one can be forced by a voters' petition.

Only one Welsh authority has held a referendum for an elected mayor, Ceredigion, and it was rejected.

What is happening on 3 May?

On 3 May three mayoral seats will be contested in England - in Bedford, Mansfield and Middlesbrough.

Who is standing?

In Bedford, independent candidate Frank Branston is standing for re-election. Challenging him will be Nicky Attenborough (Conservative), Randolph Charles (Labour), Christine McHugh (Liberal Democrat), and Justina McLennan (Green).

In Mansfield, the local Labour MP Alan Meale will take on the incumbent, independent mayor Tony Egginton. Also standing are Aaron Beattie (Conservatives) Phillip Burman (Liberal Democrat) and Mary Button (Green).

In Middlesbrough, Independent Ray Mallon will be defending his seat against Joe Michna (Liberal Democrat), Charles Rooney (Labour) and Dorothy Smith (Conservative).