MPdB > by-elections
Douglas Carswell left UKIP to become an independant on 25th March 2017 and, much to UKIP's annoyance, did not trigger a by-election.
Wikipedia has an excellent page on these which is recycled below.
Switches of seats between parties are colour-coded.
|Manchester Gorton||4 May 2017||cancelled||Gerald Kaufman (Lab)||died age 86|
|Stoke on Trent Central||23 Feb 2017||Gareth Snell (Lab)||-2.1%||Tristram Hunt (Lab)||new job at V&A|
|Copeland||23 Feb 2017||Trudy Harrison (Con)||+6.7%||Jamie Reed (Lab)||new job at Sellafield|
|Sleaford and North Hykeham||8 Dec 2016||Caroline Johnson (Con)||-0.3%||Stephem Phillips (Con)||irreconcilable differences|
|Richmond Park||1 Dec 2016||Sarah Olney (LibDem)||+21.73%||Zac Goldsmith (Con)||3rd Heathrow runway|
|Witney||20 Oct 2016||Robert Courts (Con)||-19.3%||David Cameron (Con)||flounced off|
|Batley and Spen||20 Oct 2016||Tracy Brabin (Lab)||n/a †||Jo Cox (Lab)||murdered|
|Tooting||16 Jun 2016||Rosina Allin-Khan (Lab)||+7.3%||Sadiq Khan (Lab)||became London mayor|
|Ogmore||5 May 2016||Christopher Elmore (Lab)||-0.8%||Huw Irranca-Davies (Lab)||to stand for the Welsh Assembly|
|Sheffield Brightside & Hillsborough||5 May 2016||Gill Furniss (Lab)||+4.1%||Harry Harpham (Lab)||death, cancer|
|Oldham West & Royton||3 Dec 2015||Jim McMahon (Lab)||+2.3%||Michael Meacher (Lab)||death|
† The conservatives, libdems and UKIP did not field a candidate because of the circumstances of the vacancy.
‡ A swing is calculated by comparing the percentage of the vote in a particular election to the percentage of the vote belonging to the same party or candidate at the previous election. Wikipedia.