By-elections to the House of Lords occur when vacancies arise among seats assigned to hereditary peers due to death, resignation, or disqualification. Candidates for these by-elections are limited to holders of hereditary peerages, and their electorates are made up of sitting Lords; in most cases the electorate are those sitting hereditary peers of the same party affiliation as the departed peer. Following the enactment of the House of Lords Act 1999, the number of hereditary peers entitled to sit in the House of Lords was reduced to ninety-two. The Earl Marshal and the Lord Great Chamberlain were entitled to sit ex officio; the remaining ninety were elected by all the hereditary peers before the passing of the reform.
Before the passing of the 1999 Act, the Lords approved a Standing Order stating that the remaining hereditary peers shall consist of:
Prior to November 2002, vacancies were automatically filled by the highest performing unsuccessful candidate in the 1999 House of Lords election that elected the departed peer.
Elections are normally required to be held within three months of a vacancy occurring, but until the end of 2024âÂÂ2026 parliamentary session, elections must be held within 36 monthsâÂÂin practice suspending by-elections whilst the role of hereditary peers in the Lords was debated (see House of Lords (Hereditary Peers) Act 2026).
The elections take place under the Alternative Vote system for elections to individual vacancies and the Single Transferrable Vote for elections to fill multiple vacancies. All those on the Register of Hereditary Peers are eligible to stand, but only sitting (the "excepted") hereditary peers of the group in question may vote for the seats reserved for a single parliamentary group. This can result in very small electorates, such as only three voters in the 2003 election of Lord Grantchester. For the 15 peers elected by the whole House, life peers may also vote.
As of September 2023, there have been 18 by-elections among Conservative peers; 19 by-elections among Crossbench peers; 2 among Liberal Democrat peers; and 2 among Labour peers. In addition, there have been 14 by-elections by the whole House.
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After the death of Lord Aberdare:
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After the death of the Lord Strabolgi:
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After the death of the Lord Ampthill:
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After the death of the Lord Reay:
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After the death of the Lord Methuen:
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After the death of the Lord Lyell:
After the death of the Lord Skelmersdale:
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After the retirement of the Countess of Mar:
After the retirement of the Lord Elton:
After the death of the Viscount Simon:
After the retirements of the Viscount Ullswater, and the Lord Colwyn:
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After the retirement of the Viscount Falkland:
After the death of the Lord Brougham and Vaux:
After the death of Baroness Strange:
After the death of the Baroness Darcy de Knayth:
After the death of the Viscount Bledisloe:
After the death of the Viscount Colville of Culross:
After the death of the Lord Monson:
After the death of the Lord Moran:
After the death of the Viscount Allenby of Megiddo:
After the retirement of the Lord Cobbold:
After the retirement of the Lord Chorley:
After the retirement of the Lady Saltoun of Abernethy:
After the retirement of the Viscount Tenby:
After the retirement of the Viscount Montgomery of Alamein:
After the removal for non-attendance of the Lord Bridges:
After the retirement of the Lord Walpole:
After the retirement of the Earl Baldwin of Bewdley:
After the retirement of the Lord Northbourne:
After the death of the Viscount Slim:
After the retirement of the Earl of Listowel:
After the death of the Lord Palmer and the retirement of the Lord Hylton:
After the death of Lord Vivian:
After the death of Lord Burnham:
After the death of Lord Mowbray and Stourton:
After the death of the Earl of Northesk:
After the death of the Earl of Onslow:
After the death of Earl Ferrers:
After the retirement of the Lord Luke:
After the death of the Lord Montagu of Beaulieu:
After the retirement of the Lord Glentoran:
Normally, by-elections must be held within three months of a vacancy occurring, but in response to the COVID-19 pandemic the House resolved in March 2020 to suspend any by-elections. Although this initial suspension was only until 8 September 2020, successive further motions extended this arrangement. Ultimately by-elections resumed in June 2021 with multiple elections held to fill six vacancies.
After the retirements of the Earl of Selborne and the Lord Denham, and the removal for non-attendance of the Lord Selsdon:
After the retirement of the Viscount Ridley:
After the retirement of the Lord Rotherwick:
After the retirement of the Lord Brabazon of Tara, and the death of the Lord Swinfen:
After the retirement of the Lord Astor of Hever, and the death of the Earl of Home:
After the death of the Earl Russell:
After the death of the Lord Avebury:
After the death of the Lord Rea:
The Labour government elected in July 2024 stated an aim to remove of the right of hereditary peers to sit in the Lords. In anticipation of imminent legislative debates, and reflecting views that "ongoing by-elections during the parliamentary consideration of a Bill would be deeply undesirable in this context", on 25 July 2024 the House of Lords passed a motion to extend the deadline for holding a by-election to 18 months. This was later extended to 36 months, as the House of Lords (Hereditary Peers) Bill was debated in Parliament.
The Bill received royal ascent on 18 March 2026, with the removal of hereditary peers to take effect at the end of the session. As the session is expected to end before the expiration of the most imminent 36-month deadline, no further by-elections are expected to take place.
From the 1707 Act of Union to the passing of the Peerage Act 1963, peers in the Peerage of Scotland elected sixteen representative peers to sit in the House of Lords. Unlike Irish peers, however, Scottish representative peers only sat for the duration of one parliament before facing re-election. By-elections were held in the Palace of Holyroodhouse to replace deceased peers. After the passing of the Peerage Act 1963, all Scottish peers were entitled to sit in the House of Lords and the election procedure was abolished.
The last Scottish representative peer by-election took place in 1959, when the Duke of Atholl was elected in place of the late Lord Sinclair.
Also, from the 1801 Act of Union to Irish independence, 28 Irish representative peers were elected from and by the Peerage of Ireland to sit in the British House of Lords. Like current hereditary peers, these representative peers sat for life terms and deceased peers were replaced in by-elections. Unlike modern hereditary peer by-elections, all peers in the Peerage of Ireland, even those who did not sit in the House of Lords, were entitled to vote. Upon the creation of the Irish Free State, the offices required to officiate these by-elections were abolished and thus no more were held, but those peers already elected kept their seats for the remainder of their lives. The last to sit in the Lords was Francis Needham, 4th Earl of Kilmorey, who died in 1961.