Image copyright AFP/Getty

Voters are casting their votes in elections across the UK, with less than an hour to go before polls close.

Elections are taking place for the Scottish Parliament, National Assembly of Wales, the Northern Ireland Assembly and for 124 councils in England.

Mayors will be elected in London, Bristol, Liverpool and Salford, with UK parliamentary by-elections held in Ogmore and Sheffield Brightside.

Police and crime commissioners are also being elected in England and Wales.

Problems were reported in Barnet, North London, where the council apologised after some people were unable to vote on Thursday morning.

The Electoral Commission said some polling stations did not have the correct lists of people's names.

Later in the morning, the council said the correct registers had been delivered and those denied a vote should come back.

Image copyright PA Image caption Ballot boxes used for voting in the Scottish Parliament election are checked before being delivered to Edinburgh's polling stations

Polling stations across the length and breadth of the country opened at 07:00 BST, with voting allowed until 22:00 BST.

Thursday's polls are the single largest test of political opinion before the next general election, which is scheduled for 2020.

Image copyright EPA Image caption David Cameron cast his vote in Westminster with his wife Samantha

Image copyright PA Image caption Labour leader Jeremy Corbyn voted in Islington

Elections to the Holyrood Parliament in Edinburgh and the devolved assemblies in Cardiff and Belfast last took place in 2011.

The SNP has been in power in Scotland since 2007, while Labour has run the Welsh government since 1999.

There is a power-sharing arrangement in place in the Northern Ireland Executive. The DUP and Sinn Fein have been the two largest parties at Stormont since 2011.

Tap here to find out which election is taking place in your area.

In total, 2,747 seats in English councils - spanning metropolitan boroughs, unitary authorities and district councils - are up for grabs. The majority of the seats were last contested in 2012.

In London, the Greater London Assembly will be elected, as will a successor to the capital's mayor Boris Johnson, who has run City Hall since 2008. Mayoral contests will also be held in Bristol, Liverpool and Salford.

Election coverage on the BBC:

Image copyright PA Image caption The London Eye was lit up in pink, the colour of the mayoral campaign, on the eve of the election to remind Londoners to vote

New MPs for the constituencies of Ogmore, in Bridgend County, and Sheffield Brightside and Hillsborough will also be chosen.

The Ogmore by-election was triggered by former Labour MP Huw Irranca-Davies's decision to stand for the Welsh Assembly. The Sheffield contest was caused by the death of sitting Labour MP Harry Harpham.

Voters in 40 police force areas in England and Wales, excluding London and Greater Manchester, will also elect a police and crime commissioner. The inaugural elections for the positions were held in 2012.

Counting will take place throughout Friday with the majority of results declared on the day.

However, some English council results will not be announced until Saturday, when the final result of the Northern Irish election is also expected.

What to expect when (all timings are estimates)

Friday 6 May

00:30 First results from councils in England - around 80 results expected overnight

01:30 First results from Scottish Parliament - results in all 129 seats expected overnight

02:15 First results from Welsh Assembly - results in all 60 seats expected overnight

Results of Wiltshire Police and Crime Commissioner election and Liverpool Mayoral contest also expected overnight

11:30 First results from around 50 councils in England to declare on Friday

15:00 First results of London Assembly elections

17:00 First preference vote share information for elections to Northern Ireland Assembly

1800 Result of first preference votes for Mayor of London (final result expected early evening)

Results of Police and Crime Commissioner elections in England and Salford Mayoral contest also expected on Friday

Saturday 7 May

14:00 Results from five remaining councils in England

16:00 Result of Bristol Mayoral contest

Result of elections to Northern Ireland Assembly expected

Sunday 8 May

16:00 Result of elections to Bristol Council (final council in England to declare)

Results of Police and Crime Commissioner elections in Wales