The opinion polls suggest a hung parliament is the likely outcome of this election. Political editor Annabelle Dickson looks at what could happen in the coming days if none of the parties reach the magic 326 seats needed to hold a majority.

What is a hung parliament?

With 650 seats in the House of Commons, the support of 326 MPs is needed to vote new laws through. When a General Election results in no single political party reaching an overall majority, this is known as a situation of no overall control, or a 'hung Parliament'.

What happens in this situation?

In a situation of no overall control the Government in power before the General Election gets the first chance at creating a government. In 2010 the Labour Government remained until the Conservatives and Liberal Democrats managed to reach an agreement. If the incumbent government is unable to command a majority, and as a result the Prime Minister is expected to resign, the leader of the largest opposition party may be invited to form a government and may do so either as a minority or in coalition with another party or parties.

The convention does not stop coalition talks among the other parties taking place - something that is very likely to happen as soon as the result becomes clear.

Is there a time limit?

In 2010 it took five days to put the coalition together, but there is no time limit.

The new Parliament meets for the first time on May 18, so David Cameron has until this date to put together a deal to keep himself in power or resign, according to civil service guidelines. The Queen's Speech is set for Wednesday, May 27.

What happens to the country while all this goes on?

Cabinet Secretary Sir Jeremy Heywood has said he believes the Prime Minister should remain in office until a deal is made. He also said that ministers who lose their seats should be allowed to remain part of a 'caretaker' government until a new administration takes power. Decisions will still need to be made.

Apart from last time, have there been other situations of no overall control?

In 1923 the Conservative party lost their majority at the general election and was unable to form a coalition. The party, led by Stanley Baldwin, lost a vote on the King's speech in January 1924. The Labour party under Ramsay MacDonald then took office and governed as a minority administration until October of that year.

In 1974 the incumbent Conservative administration lost its majority. Edward Heath remained as Prime Minister for a few days while he tried to form a coalition. The General Election was held on a Thursday, and it was not until the Monday that Edward Heath resigned as Prime Minister having failed to put together a coalition.

In a second general election that year, Labour was returned with an overall majority of three but by 1977-78 the Labour Government had to systematically draw on the support of the Liberals. A Lib-Lab pact was formed, which lasted until May 1978.