People with regional accents should be protected from "accentism" alongside the fight against racism, ageism and sexism because it makes them feel "fake" when they "posh up" while talking, it has been claimed.
Employers should state in writing that job applicants' accents will not be used against them and application forms should request applicants to "state their accent" alongside other identities such as gender, sexual orientation, religion, age and race, according to Manchester University linguist, Dr Alex Baratta.
Dr Baratta says accentism is the "last taboo" alongside discrimination on other grounds like colour or sex.
Dr Baratta, based at the University's Manchester Institute of Education said: "We should acknowledge that any form of workplace discrimination, to include accentism, should not be tolerated in a society which seeks to be more inclusive.
"This is why 'accentism' should be taken seriously as a problem which affects many of us.
"Clearly, most people modify their accent not because they lack pride in it, quite the opposite in fact. It's actually because they fear the negative perceptions others might have of them if they don't, especially in work-related contexts."
Dr Baratta, who is from Los Angeles, added: "As with George Bernard Shaw's quote, 'It is impossible for an Englishman to open his mouth without making some other Englishman hate or despise him.'
"I don't know if one prejudice is better then the other, you're the wrong colour, the wrong sex, wrong age, wrong accent."
His call to battle accentism comes after his research claims to show people who "posh up" their accent feel themselves as frauds or fakes.
Though accent modification is common, Dr Baratta said it can threaten the way we feel about personal identity, often causing anger and frustration.
Workplace meetings with 'posh' sounding senior managers, he says, can be especially stressful for an individual with a more pronounced regional accent along with job interviews and even speaking on the phone, he said.
Dr Baratta's research is based on an ongoing survey of children, students and staff from different institutions and schools, involving 98 people so far.
It reveals that while most accept the practice, a third of respondents say they feel like a fraud when they consciously modify their accent.
Though accent modification and the relationship between accent and identity are well researched, it is the first time anyone has attempted to investigate how accent modification in Britain affects the way we feel about ourselves.
Dr Baratta added: "Many Brits consciously modify their accent in social situations as a means to create a better impression.
"While this is a common practice, we should not assume that it is accepted by all speakers without issue.
"As part of my ongoing research, many participants see accent modification as synonymous with selling out and a clear threat to their sense of self.
"This is especially true in education, where teachers in particular may feel pressure to modify their regional accent in order to be perceived in a more positive light by students and fellow staff alike.
"My point is perfectly illustrated by an Ofsted inspector who last year told a Cumbrian teacher working in a Berkshire school to sound 'more southern'."
Examples revealed by Dr Baratta's research include a teacher from Rossendale, Lancashire, "felt disgusted" with himself for modifying his accent at a job interview, a Mancunian woman felt "fake, angry and upset" for modifying her accent with her lecturers, and believes she is "betraying" who she really is and a Liverpudlian stated that accent modification, mostly practised in business contexts, leaves him feeling "whipped".