Biggest byelection swings in the past 20 years

Two-party percentage point swing, UK byelections

Con to Ukip 2014 Clacton

44.1

Lab to Respect 2012 Bradford West

36.6

Con to Lib Dem 2021 North Shropshire

34.1

Con to Lib Dem 2022 Tiverton and Honiton

29.9

Con to Lib Dem 2023 Somerton and Frome

29.0

Lab to Lib Dem 2003 Brent East

28.9

Con to Ukip 2014 Rochester and Strood

28.3

Lab to Lib Dem 2004 Birmingham Hodge Hill

26.7

Con to Lib Dem 2021 Chesham and Amersham

25.1

Con to Lab 2023 Selby and Ainsty

23.8

Lab to SNP 2008 Glasgow East

22.6

Con to Lib Dem 2016 Richmond Park

21.7

0

10

20

30

40

Con to Ukip 2014 Clacton

44.1

Lab to Respect 2012 Bradford West

36.6

Con to Lib Dem 2021 North Shropshire

34.1

Con to Lib Dem 2022 Tiverton and Honiton

29.9

Con to Lib Dem 2023 Somerton and Frome

29.0

Lab to Lib Dem 2003 Brent East

28.9

Con to Ukip 2014 Rochester and Strood

28.3

Lab to Lib Dem 2004 Birmingham Hodge Hill

26.7

Con to Lib Dem 2021 Chesham and Amersham

25.1

Con to Lab 2023 Selby and Ainsty

23.8

Lab to SNP 2008 Glasgow East

22.6

Con to Lib Dem 2016 Richmond Park

21.7

0

10

20

30

40