Wakefield and Tiverton by-elections: Polls open in crucial by-elections for Boris Johnson - why are they being held and when will the results be known?

Voters are going to the polls in two Westminster by-elections today with the results likely to pile more pressure on Prime Minister Boris Johnson

Two by-elections taking place on the same day is fairly common in British politics – but a Government losing two by-elections on the same day is extremely rare.

The last time it happened was more than 30 years ago.

On November 7 1991, the Conservative government of John Major lost the seat of Langbaurgh in Cleveland to Labour and also Kincardine & Deeside to the Liberal Democrats.

Boris Johnson is facing two crucial by-elections

If the Conservatives were to lose both of the by-elections taking place on Thursday – in Wakefield and in Tiverton & Honiton – it would be only the seventh time a government has suffered such a double defeat since the Second World War.

Wakefield in West Yorkshire was won by the Tories from Labour at the 2019 general election, but Labour is now hoping to take it back.

How big a swing is needed?

To overturn the Conservative majority of 3,358, Labour needs a swing in the share of the vote of 3.8 percentage points – in other words, four in every 100 people who voted Tory in 2019 would need to switch to Labour.

A far bigger swing is required for the Tories to lose the seat of Tiverton & Honiton in Devon.

The Liberal Democrats are the main challenger in this constituency, but it would take a swing of 22.8 points for them to win, or the equivalent of 23 in every 100 people who voted Conservative in 2019 switching directly to the Lib Dems.

This is a smaller change than the one achieved by the Lib Dems in the North Shropshire by-election in December last year, when they took the seat from the Conservatives on a 34.1 point swing.

It would also be smaller than the 25.2 point swing in the Chesham & Amersham by-election in June 2021, which again saw the Liberal Democrats take the seat from the Tories.

If the Lib Dems manage a swing in Tiverton & Honiton of more than 25.4 points, it would rank as one of the 10 largest swings against a government since 1945 in a by-election which saw a change in both party and MP.

The biggest swing of this kind took place in July 1993 at the Christchurch by-election, which was won by the Lib Dems on a 35.4 point swing from the Conservatives.

The Tiverton & Honiton seat has been held by the Tories since its creation in 1997.

Why are the by-elections being held?

The Wakefield by-election was sparked by former Tory incumbent Imran Ahmad Khan being found guilty of sexually assaulting a boy. A poll has already suggested the Tories could lose the by-election by as much as 20 points in an indication the revelations about Downing Street lockdown-busting gatherings have hit the party’s popularity in a battleground seat.

Wakefield had been a Labour seat continuously from 1932 until 2019, when it was won for the Conservatives by Khan.

The Tiverton & Honiton seat has been held by the Tories since its creation in 1997.

MP Neil Parish won a majority of 24,239 at the 2019 general election, but resigned earlier this year after admitting watching pornography in Parliament.

When will the results be known?

The results in both contests are expected to be declared between 4am and 6am on Friday.