Political parties are bracing themselves for Thursday's local elections results, held nearly everywhere in England outside London.

In total 10,455 of the 19,585 council seats in the country were up for grabs, spread across 312 of the 386 local authorities.

One-third of seats on all 36 of the metropolitan boroughs were contested. In 25 unitary authorities the whole council is being chosen, while in another 20 only one-third were up for election.

Of the district councils, 153 elected the entire council and 78 elected a third.

This was the biggest election in the local cycle in England because polling for councils electing all councillors every four years and those electing one-third of councillors falls on the same year.

There were also elections for three elected mayors in Bedford, Mansfield and Middlesbrough.

Unlike local elections in Scotland - which this year operate under the singe transferable vote, a form of proportional representation - councillors in England are elected using the first-past-the-post system.

This is the same as that used in Westminster elections, although while some councils use single-member wards, others use multi-member wards.

The seats being fought this year were last up for grabs in 2003 or 2004.

Opinion polls

The nature of local elections makes accurate polling difficult, but many observers have been predicting that Labour is heading for a poor result.

An analysis by professors Colin Rallings and Michael Thrasher of Plymouth University's elections centre using Labour's performance in recent council by-elections has shown Labour trailing in third place with a national equivalent vote of 24 per cent.

They suggest the Conservatives will have a 39 per cent share of the vote and the Liberal Democrats 29 per cent.

This would result in the Tories winning around 330 seats, Labour losing around 500 and the Lib Dems gaining 110.

Authorities to watch include that in Dartford, traditionally a bellwether seat having returned an MP from the governing party at every general election since 1964.

The Electoral Administration Act 2006 has made a series of changes to these elections which will affect the timing of the results.

Polling was extended to the same length as that in general elections, meaning stations were open for an extra hour - until 10pm - having opened at 7.00am.

To combat the kind of fraud seen in Birmingham in 2004 all postal votes now have to have a signature and date of birth, and returning officers have been told to verify these details on at least one in five postal votes.

As a result, many councils have moved their count from the traditional time after polling on Thursday to Friday morning.

Some 169 of the 312 councils have decided to wait until Friday, when counts are also cheaper, meaning a clear picture may not emerge before Friday afternoon.

Delays are likely to be longer in rural areas, due to the greater distances involved and the added complication of parish councils in many areas.