The count

The UK's 45,000 polling stations close at 2200 on election day.

The ballot boxes in each constituency are then sealed and taken to a central location such as a town hall or leisure centre.

Counting does not have to take place overnight but the returning officer has a duty to make arrangements "as soon as practicable after the close of poll", and in practice the vast majority of counts begin immediately.

In 1997, 629 of the 659 seats were counted overnight compared to 597 in 1992.

This year the Yorkshire constituency of Richmond will count overnight, having not done so in 1997.

This is because it is the seat where Tory leader William Hague stands and there will be huge media interest this time compared with 1992 when he was Welsh Secretary.

The count begins

The ballot papers are counted by teams of specially recruited people - normally local government staff and people used to handling large numbers of paper items such as bank workers.

First, they count the number of papers in each ballot box to make sure it tallies with the record of those issued.

Ballot box

Once that is completed satisfactorily, the tellers separate out the votes for each candidate and bundle them into groups of 50. These are then added to get the final result.

While the counting is going on, it is monitored by the candidates and their representatives to ensure fair play.

It is also possible for the parties to get an early indication of how they are doing by comparing the figures from key wards with the same ballot boxes in previous elections.

Spoiled ballots

Every count contains ballot papers that are disallowed. This can happen for the following reasons:

No official mark,

Voting for more than one candidate,

Writing or marks by which the voter can be identified,

Containing no mark, or

Containing marks that make the voter's intention uncertain.

In cases of doubt, the returning officer makes a decision in the presence of the candidates or their agents.

The officer's decision is final but can be challenged by an election petition.

Challenge and rejection

This happened in 1997 in Winchester, where the Liberal Democrat Mark Oaten defeated his Tory rival, Gerry Malone, by just two votes.

Liberal Democrat MP Mark Oaten defeated his Tory rival, Gerry Malone, by just two votes

Mr Malone felt that 55 ballot papers in his favour had been incorrectly ruled as spoiled because there was no official mark. He went to court and a by-election was ordered.

But while the courts ruled in Mr Malone's favour, the voters of Winchester took a rather different view - this time electing Mr Oaten by the massively increased margin of 21,556.

The number of spoiled papers tends to rise when more than one type of election is held on the same day.

In 1997, local elections were held on the same day in many constituencies and 93,048 papers were rejected, more than double the total in 1992.

The same happened in 1979 when 117,848 ballot papers were spoiled.

Recounts

When the count is complete, the returning officer discusses the results with the candidates or their agents.

If the result is close, or if a candidate falls just short of the 5% necessary to save their deposit, then a recount can be requested. The decision on whether to allow one is made by the returning officer.

Recounts usually start by counting the bundles of 50 votes, but candidates can request that individual bundles be checked to make sure none has been allocated incorrectly.

In the case of very close results, a complete recount can be ordered.

There is no formal limit to the number of recounts, but if the same result keeps coming up then the returning officer is likely to rule that further requests are unreasonable.

Tied results impossible

There has never been a tie in a UK general election and there never will be.

Since 1945, the smallest margin recorded is two in the case of Winchester above. Prior to 1997, the closest results were in the Conservative victory in Peterborough in 1966 and Labour's win in Carmarthen which in February 1974 - both by three votes.

In the unlikely event that recounts have failed to separate the two or more leading candidates, the returning officer is required by law to settle the matter immediately.

He or she can use any random method such as tossing a coin, but the recommended way is to ask each candidate to write their name on a blank slip of paper and place it in a container.

The returning officer then pulls out one of the slips and allocates one extra vote to that candidate, making them the winner by a single vote.

Race to declare

Once the votes have been counted and the candidates have declared themselves satisfied with the procedure, the returning officer must announce the result without delay.

In fact, some constituencies race to be the first to declare - winning themselves public attention in the process.

Sunderland South has been first to declare in the last two elections - after just 46 minutes in 1997 - with Torbay, Guildford and Reigate usually well to the front in the past 30 years or so.

The returning officer announces the total number of votes cast, and the number for each candidate.

They end with the words "I hereby declare that (candidate name) is elected to serve as Member of Parliament for the constituency of..."

The victorious candidate then makes a speech - followed by his or her rivals - in which traditionally they thank their party workers and say how proud they are to represent the electorate.