Hereditary peers are titles and may be elected to serve in the House of Lords under the provisions of the House of Lords Act 1999 and the Standing Orders of the House of Lords. The Act excluded all hereditary peers who were not also life peers except for two holders of royal offices plus ninety other peers, to be chosen by the House.

Before the enactment of the Act, the House approved a Standing Order stating that the remaining hereditary peers shall consist of:^[1]

• 2 peers to be elected by the Labour hereditary peers
• 42 peers to be elected by the Conservative hereditary peers
• 3 peers to be elected by the Liberal Democrat hereditary peers
• 28 peers to be elected by the Crossbencher hereditary peers
• 15 peers to be elected by the whole House
• The holders of the offices of Earl Marshal (the Duke of Norfolk) and Lord Great Chamberlain (currently the Baron Carrington, who was already elected as a Crossbench peer) to be ex officio members

The total number and sub-composition set out above reflects a compromise to ensure passage of the Act through the House reached between then-Prime Minister Tony Blair and the leader of the opposition Conservatives in the Lords, Viscount Cranborne (known since his father's death in 2003 as the Marquess of Salisbury), a descendant of the last Prime Minister to sit in the Lords throughout the entirety of his premiership. The number elected by each group reflected the relative strengths of the parties among hereditary peers at that time. Historically, the Conservatives had predominated in the House since 1890; it was this entrenched position which led to the removal of the absolute power of veto from the House of Lords by the Parliament Act 1911 and was the chief catalyst for the removal of most peers in 1999.^{[citation needed]} The House of Lords Act 1999 reduced the proportion of Conservative peers in the House from 41% (in April 1999) to 33% (in June 2000), and the proportion of hereditary peers in the House from 59% to 13%.^[2]

The fifteen peers elected by the whole house were intended to provide a group of experienced members ready to serve as Deputy Speakers or other officers.

The initial elections^[3] took place before the House of Lords Act took effect;^{[dubious – discuss]} therefore all hereditary peers could vote in those elections. From the end of the 1998–1999 session of parliament until the following session, vacancies (usually triggered by death) were to be filled by runners up in the initial elections. Two Crossbench peers, Lord Cobbold and Lord Chorley, returned to the House this way, having sat before 1999. Since then, vacancies among the group of 15 peers have been filled through by-elections, with all members of the House entitled to vote. The Procedure Committee has recommended that any peer elected at a by-election in this category should not be expected to serve as a Deputy Speaker.^[4] In by-elections to fill vacancies in the political groups, only hereditary peers of that group sitting in the House may vote.

As of November 2022, there are 4 dukes, 25 earls, 15 viscounts, 45 barons and 2 Lords of Parliament among the 91 hereditary peers entitled to sit in the House of Lords.

Only those with titles in the Peerages of England, Scotland, Great Britain and the United Kingdom are currently eligible for a seat. Peers in the Peerage of Ireland are only eligible if they hold a title in one of the other peerages, but if elected, they may use their Irish peerage whilst in the Lords; for instance, the present Earl of Arran, whose highest title is an Irish one, is entitled to a seat as Lord Sudley, his subsidiary title in the UK peerage, but sits using his highest, Irish, title.

Ex officio members

Earl Marshal

The Earl Marshal is an hereditary post held by the Duke of Norfolk.

Lord Great Chamberlain

The Lord Great Chamberlain is a hereditary office in gross post among the Cholmondeley, Heathcote-Drummond-Willoughby and Carington families.

In 1902 it was ruled by the House of Lords that the then joint office holders (the 1st Earl of Ancaster, the 4th Marquess of Cholmondeley, and the Earl Carrington, later Marquess of Lincolnshire) had to agree on a deputy to exercise the office, subject to the approval of the Sovereign. Should there be no such agreement, the Sovereign should appoint a deputy until an agreement be reached.^[5]

In 1912 an agreement was reached. The office, or right to appoint the person to exercise the office, would thereafter rotate among the three joint office holders and their heirs after them, changing at the start of each successive reign. Cholmondeley and his heirs would serve in every other reign; Ancaster and Carrington would each serve once in four reigns.^[6]

Elected by the whole House

Sitting

Deceased

Resigned

Pursuant to section 1 of House of Lords Reform Act 2014

Elected by the Conservative hereditary peers

Sitting Conservative peers

Deceased Conservative peers

Resigned Conservative peers

Pursuant to section 1 of House of Lords Reform Act 2014

Removed Conservative peers

Pursuant to section 2 of House of Lords Reform Act 2014

Elected by the Crossbencher hereditary peers

Sitting Crossbench peers

Deceased Crossbench peers

Resigned Crossbench peers

Pursuant to section 1 of House of Lords Reform Act 2014

Removed Crossbench peers

Pursuant to section 2 of House of Lords Reform Act 2014

Elected by the Labour hereditary peers

Sitting Labour peers

Deceased Labour peers

Elected by the Liberal Democrats hereditary peers

Sitting Liberal Democrats peers

Deceased Liberal Democrats peers