The Conservatives are heading for an electoral defeat on the scale of the 1997 Labour landslide, according to the predictions of the most authoritative opinion poll in five years.

The YouGov survey of 14,000 people forecasts that the Tories will retain just 169 seats, while Labour will sweep to power with 385 – giving Sir Keir Starmer a 120-seat majority.

The poll indicates that every ‘Red Wall’ seat won from Labour by Boris Johnson in 2019 will be lost and the Chancellor, Jeremy Hunt, will be one of 11 Cabinet ministers to lose their seats. The Tories will win 196 fewer seats than in 2019, more than the 178 Sir John Major lost in 1997.

Sidmouth Herald: Richard Foord and Simon Jupp, competing for the Honiton & Sidmouth seat

However, the political map of Devon remains mainly blue, with the Conservatives expected to hold the new Honiton & Sidmouth constituency. The current Tory MP for East Devon, Simon Jupp, will be up against the current Tiverton & Honiton Liberal Democrat MP Richard Foord for this seat. The YouGov poll predicts that the Conservatives will win 33 per cent of the vote, the Lib Dems 25 per cent, Labour 20 per cent, Reform UK 15 per cent, the Green Party 4 per cent and ‘Others’ 3 per cent.

Conservative wins are also predicted in the two neighbouring constituencies newly created by boundary changes -  Exmouth & Exeter East and Tiverton & Minehead. However Exeter, a strong Labour seat, remains a pinpoint of red in the Tory-blue map, and Labour is expected to take Plymouth Moor View from the Conservatives.

In North Devon the Liberal Democrats are forecast to take the seat from the Tories – contributing to their predicted 48 seats which would make them a significant Parliamentary force once again.

The YouGov predictions are based on a multilevel regression and post-stratification (MRP) model, which is a way of using large national samples to estimate public opinion at a local level.

It’s YouGov’s first MRP since the new parliamentary constituency boundary proposals were finalised. YouGov said: “While this is the first time an election will be fought using these constituencies, notional results calculations allow us to see what the outcome in each seat would have been if the last election had used those boundaries, and therefore which seats would be changing hands.”