Who can vote?

To be able to vote in a UK Parliamentary election, you must be:

Aged 18 or over,

A citizen of the UK, a Commonwealth country or the Republic of Ireland,

Resident in a constituency and on the electoral register, and

Not in a category barred from voting (see below).

In addition, British citizens who have lived abroad for up to 20 years may vote, and voters in Northern Ireland must have lived in the constituency for the previous three months.

In all, more than 44 million people meet these criteria.

Barred from voting

There are certain categories of people not allowed to vote:

Members of the House of Lords. The ejection of most hereditary peers from the Lords in 1999 means that they will be able to vote - and stand - for the first time in a general election.

Those in prison.

People convicted of electoral malpractice are barred for five years.

Echoing the rather arcane language of the legislation, "idiots" may not vote and "lunatics" only during their lucid periods. Those compulsorily detained in psychiatric hospitals, for example, cannot vote.

Hereditary peers can now vote and stand in the general election

It is commonly thought that members of the Royal family are not allowed to vote, but this is not true.

The Queen can vote, as can members of her family, but they do not do so because in practice it would be considered unconstitutional.

The electoral register

Traditionally, the register was compiled annually for each constituency by the local electoral registration officer.

Employed by the local authority, he or she sent out forms to every household, asking the names of eligible voters who would be resident on the qualifying date - 10 October in Britain, 15 September in Northern Ireland.

This was published on 16 February each year, and remained in force until 15 February the following year. It was, therefore, already four months out of date when it was published - and 16 months out of date by the end of its life.

In order to address these inefficiencies, the Representation of the People Act 2000 introduced some significant changes to the way the electoral register operates.

The one published on 16 February 2001 becomes the baseline for a "rolling register" which allows people to be added to and deleted from the electoral register throughout the year - rather than basing registration on residence on a single annual qualifying date.

For the first time homeless people will be able to register to vote

If the general election is held on 3 May 2001, for example, any changes or applications to register received by electoral registration officers up to 12 March should be accepted under these new arrangements.

The changes also allow mental patients who are not detained offenders, homeless people, and those remanded in custody to register as electors.