One-termers: MPs who stood down after only one term (not counting those who had served previous terms in Parliament) or who never completed a full term of Parliament after being elected at a general election (list is since 1979):
1979-1983:
Labour:
Andy McMahon (forced out by boundary changes)
Helen McElhone (forced out by boundary changes)
Reg Race (forced out by boundary changes)
Sheila Wright
Conservative:
Tom Benyon (forced out by boundary changes)
Sheila Faith (tried and failed to migrate to another constituency after boundary changes made her seat notionally Labour)
Jocelyn Cadbury (committed suicide in 1982)
Keith Wickenden
DUP:
John McQuade (67 when elected in 1979)
Anti H-Block:
Bobby Sands (died on hunger strike in 1981)
1983-1987:
UUP:
Jim Nicholson (sought re-election over opposition to Anglo-Irish agreement and lost to the SDLP)
1987-1992:
Labour:
Michael Carr (died in 1990 after only 47 days in office)
Pat Wall (died in 1990)
Conservative:
Alan Amos (resigned after an alleged act of indecency)
1992-1997:
Labour:
Jimmy Boyce (died of cancer in 1994)
Conservative:
Hartley Booth (forced out by boundary changes)
Michael Stephen (forced out by boundary changes ipso facto)
Roy Thomason (stood down over financial problems regarding his nursing home companies)
Judith Chaplin (died from surgery complications in 1993)
Stephen Milligan (died from autoerotic asphyxiation in 1994)
1997-2001:
Labour:
Tess Kingham
Jenny Jones
Liberal Democrats:
Donald Gorrie (64 when elected in 1997)
SNP:
Alasdair Morgan (to avoid dual mandate)
John Swinney (to avoid dual mandate)
2001-2005:
Labour:
Paul Daisley (died of cancer in 2003)
2005-2010:
Labour:
Kitty Ussher
Jim Devine (due to expenses fraud for which he was later jailed)
Liberal Democrats:
David Howarth
Independent:
Peter Law (died of cancer in 2006)
2010-15:
Conservative:
Aidan Burley (after a scandal)
Chris Kelly
Dan Byles
Lorraine Fullbrook
Mike Weatherley
Laura Sandys
Jessica Lee
Louise Mensch (resigned in 2012)
Liberal Democrats:
Ian Swales
2015-17:
Labour:
Harry Harpham (died of cancer in 2016)
Jo Cox (murdered in 2016)
Conservative:
David Mackintosh (regarding investigations into Northampton FC)
(ex) SNP:
Natalie McGarry (over embezzlement of Women for Independence funds)
Michelle Thomson (see above)
Current Parliament (2017-present):
Labour:
Fiona Onasanya (recalled in 2019 after being convicted of perverting the course of justice in 2018; did not stand in by-election caused by successful recall petition)
Sinn Fein:
Barry McElduff (resigned after suspension of Sinn Fein whip following "Kingsmill" stunt)