The leaders of Britain's major political parties cast their votes in Britain's most unpredictable election in decades on Thursday (7 May).

Prime Minister David Cameron's Conservatives and Ed Miliband's opposition Labour Party have been neck and neck in opinion polls for months, indicating neither will win enough seats for an outright majority in the 650-seat parliament.

Labour's campaign has focused on pledging to cut the deficit each year, raise income tax for the highest 1% of earners and defend the interests of hard-pressed working families and the treasured but financially stretched national health service.

The Conservatives portray themselves as the party of jobs and economic recovery, promising to reduce income tax for 30m people while forcing through further spending cuts to eliminate a budget deficit still running at 5% of gross domestic product.

Ukip's main focus has been on curbing immigration and getting Britain out of the European Union.

In his trademark cheery style, leader Nigel Farage gave the thumbs up as he arrived to cast his vote in his constituency of Ramsgate.

If neither of the two main Labour and Conservative parties wins an overall majority, talks will begin on Friday with smaller parties in a race to strike deals.

That could lead to a formal coalition, like the one Cameron has led for the past five years with the Liberal Democrats. Or it could produce a fragile minority government making trade-offs to guarantee support on key votes.

The SNP, which some polls predict could even sweep the board in Scotland wiping out Scottish Labour, could end up playing a key role in any power-sharing talks which will stoke Scottish desire for secession.