Dr Frank Luntz, an American political analyst, said on the first day of the Conservative Party conference that any MP with less than an 8,000 majority should be concerned about being re-elected.
Simon Jupp was the only Devon Tory to get less than a 12,000 majority in 2019’s general election, receiving 6,708 votes more than an independent candidate in East Devon.
The Conservatives held onto 10 seats, with Luke Pollard for Labour winning the remaining two in Plymouth, Sutton and Devonport and Sir Ben Bradshaw retaining the Labour seat he has held since 1997 in Exeter.
Liberal Democrat Richard Foord reduced the Tory stronghold to nine seats by winning a by-election in Tiverton and Honiton last year after the resignation of Tory MP Neil Parish, who stepped down after admitting he watched pornography in the House of Commons.
Mr Foord and Simon Jupp will battle for the new Honiton and Sidmouth seat at the next election.
Labour has effectively conceded that it can’t win much in Devon, however well it is doing in the national polls.
According to a leaked list, it will not prioritise its resources trying to win in Torbay, the newly configured constituencies of Honiton and Sidmouth, Tiverton and Minehead, Torridge and Tavistock, or North Devon.
And despite the Liberal Democrats believing they can take seats from the Tories, Conservative dominance in the county is likely to remain, according to Dr Luntz.
The pollster, who has David Cameron and Barrack Obama among his fans, has earlier told Tory backbenchers that anyone with a margin of less than 15,000 should prepare to lose their seats. He now admits this figure was “provocative”.
Dr Luntz told “Times Radio” that some Tory MPs would be shocked on election day.
“Some of these MPs have already understood the frustration with the public, understood the tension between the economy and the environment, which is the conversation I kept hearing,” he said.
“[They] expressed their frustration about immigration, crime and the roads, don’t see that Labour’s going to bring about the change they want and they’re already winning back disaffected Tories.”
The next general election has to take place by January 28, 2025.
While no official announcement has been made, betting is increased on the chances of a May poll.
The Devon MPs in the 2019 general election won with these majorities:
South West Devon, Gary Streeter (Con), majority 21,430
Tiverton and Honiton, Neil Parish (Con), 24,239
Torridge and West Devon, Geoffrey Cox (Con), 24,992
Torbay, Kevin Foster (Con), 17,749
Newton Abbot, Anne Marie Morris (Con), 17,501
Plymouth Moor View, Johnny Mercer (Con) 12,897
East Devon, Simon Jupp (Con), 6,708
Totnes, Anthony Mangnall (Con), 12,724,
North Devon, Selaine Saxby (Con), 14,813
Central Devon, Mel Stride (Con), 17,721.