It’s more than 30 years since an incumbent failed
In much of the discussion on Richmond Park a lot has been made of the 19%+ CON>LD swing that the yellows achieved in Witney which is almost exactly what is required in Thursday’s contest. The only difference is that in this latest by-election the LDs are fighting the incumbent and there is a well recorded incumbency effect.
In fact if you look at other by-elections where the incumbent seeks re-election then they usually do so. In the final year of the last Parliament both Carswell on Reckless switched from the Tories to UKIP and resigned seats to fight by-elections. Both held on though Reckless by a much smaller margin than UKIP’s private polling said he would. In the latter the Tories threw absolutely everything at stopping Reckless because it was paramount that no other CON MPs should follow the same course in the run-up to GE2105.
In the 2005-2010 parliament we had David Davis’s resignation on civil liberties and his subsequent by-election success albeit helped by some other parties standing aside.
The biggest example of the incumbency effect came in Northern Ireland on January 23rd 1986 when every single unionist MP of whichever brand, 15 of them in all, had resigned in protest against the Anglo-Irish Agreement. Each of their parties agreed not to contest seats previously held by the others, and each outgoing MP stood for re-election. All but one of them succeeded. The SDLP managed to take Newry & Armagh.
In England you’ve got to go back to June 3rd 1982, at the height of the Falklands war, to find a by-election failure by an incumbent. Bruce Douglas-Mann had switched from Labour to the SDP in Mitcham & Morden only to lose the by-election to the Tories.
Whether the super-charged atmosphere created by the Falklands war will be matched by feelings on BREXIT in Richmond Park and North Kingston on Thursday we’ll have to see.