One of Britain's top electoral analysts has predicted that the Conservatives would lose the next general election more severely than they did in Tony Blair's landslide victory in 1997, following Labour's two historic by-election victories on Friday.
Labour achieved a great swing of 23.9 points in Tamworth, Staffordshire, which is high enough to be ranked as the second highest swing by Labour at a by-election since 1945.
Mid-Bedfordshire was also taken by Sir Keir Starmer's party, which managed to overthrow the highest numerical Conservative majority (24,664).
In the wake of the results, Sir John Curtice, a professor of politics at Strathclyde University, said on BBC Radio 4's Today programme: "It is reasonable to argue that the Conservative Party faces the serious prospect of losing the next General Election heavily, and maybe even more heavily than they did in 1997.”
Here are some of the biggest by-election swings.
What is a by-election?
When an MP resigns from their House of Commons seat during a parliament, either by resignation, death, disqualification, or expulsion, a local election known as a by-election is held.
The biggest by-election swings
1983 Bermondsey by-election - 44.2
On February 24, 1983, a by-election was conducted in the South London constituency of Bermondsey as a result of Labour MP Bob Mellish's departure. Simon Hughes was the Liberal Party candidate, and Peter Tatchell was the Labour Party candidate.
With the majority of votes cast, the Liberals won the seat after a fierce campaign in which they made significant gains. Labour's share of the vote dropped from 63.6 per cent in May 1979 to 26.1 per cent as Tatchell finished well behind. Robert Hughes, the Conservative candidate, received only fourth place and lost his deposit.
The Bermondsey by-election in 1983 continues to have the biggest swing in British political history, at 44.2 per cent.
2014 Clacton by-election - 44.1
Douglas Carswell, the Conservative MP for Clacton, defected to UKIP and then resigned his seat to run for re-election as its candidate, which sparked the by-election.
Retaining his seat with 59.7 per cent of the vote, Carswell then became UKIP's first elected Member of Parliament. Conservative finished second, followed by Labour. The outcome was the largest rise in the vote share for any party in any by-election in history, according to Strathclyde University politics professor John Curtice.
1973 Lincoln by-election - 43
Dick Taverne, a Labour MP for Lincoln, was re-elected in the March 1, 1973, Lincoln by-election after the Lincoln Constituency Labour Party rejected him due to his pro-Common Market stance.
Although Taverne helped fuel a lot of talk following the by-election on the potential creation of a new centrist party, Taverne was unable to sustain his lead.
1967 Hamilton by-election - 37.9
After Tom Fraser, the former Labour MP, resigned to become the chairman of the North of Scotland Hydro-Electric Board, a by-election was held.
From 1945 until 1966, when only the Conservatives had stood up to them, the constituency had been a safe seat for Labour, which had received almost two-thirds of the vote there.
Winnie Ewing of the Scottish National Party unexpectedly won the election. With a swing of almost 38 per cent, the SNP defeated the Labour Party to capture the seat, garnering 46 per cent of the vote in a constituency that they had not even run in the 1966 general election. Although Ewing lost her seat in the subsequent general election, the SNP has maintained constant representation in the House of Commons ever since.
2012 Bradford West by-election - 36.6
The result, which George Galloway of the Respect Party dubbed the "Bradford Spring" (by comparison with the Arab Spring), saw Galloway defeat the Labour Party candidate by a significant majority, surprising everyone. The outcome of the election, according to Galloway, was Bradford's "peaceful democratic uprising" equivalent of the August 2011 riots that erupted across England.
The Joseph Rowntree Reform Trust commissioned a report to examine the campaign due to the unexpected outcome.
1993 Christchurch by-election - 35.4
On July 29, 1993, a by-election was conducted in the Christchurch British House of Commons seat in response to the passing of Conservative MP Robert Adley.
The outcome showed that the Liberal Democrats had gained more than 60 per cent of the vote, about twice as many as the Conservatives, and were noteworthy for having made the swing needed to win such a strong Conservative seat.
The 35.4 per cent swing, as of December 2021, is still the sixth-biggest swing in British politics history.
Other large by-election swings:
- 2021 North Shropshire - 34.2, Conservative to Liberal Democrats
- 1988 Glasgow Govan - 33.1, Labour to SNP
- 1972 Sutton and Cheam - 32.6, Conservative to Liberal
- 1979 Liverpool Edge Hill - 30.2, Labour to Liberal
- 2022 Tiverton and Honiton - 29.9, Conservative to Liberal Democrats
