In the preface to Pygmalion, George Bernard Shaw famously wrote: 'It is impossible for an Englishman to open his mouth without making some other Englishman hate or despise him.'

More than century on, that sentiment seems to be gaining credence rather than fading away, particularly at a time when there are movements to preserve and sustain the beauty of England's regional accents.

While there is no suggestion of hate, or being despised, in the latest incarnation of this stance, it is seemingly being applied in a rather different way and used – in judgment – upon younger people entering the teaching profession.

Evidence has emerged that some trainee teachers from northern England have been told to modify their accents if they want to be better understood in the classroom as they teach children phonics – used in primary schools to teach reading and writing.

However, those with 'southern accents' were less likely to be asked to modify their speech.

As someone who comes from Lincolnshire, when accents are discussed I'm neutral; I've worked in Portsmouth and been branded a northerner, and in Sheffield and South Shields where they regarded me as a southerner.

I'm neither and never will be, which leads me to think that categorising people because of their accents is veering onto highly dangerous ground, particularly in the teaching profession which in other areas is so sensitive about inclusion in terms of race, creed, ethnicity and skin colour.

That's why it always surprises me that regional accents seem to be 'fair game' whereas these other areas are such sensitive ground.

Added to that, we'd find ourselves in dangerous territory challenging Scottish, Irish or Welsh accents in the same way.

This issue has emerged – though not for the first time, I may add – via a small-scale study by Manchester University, based on interviews with 11 trainee teachers from two northern universities, and 12 trainee teachers drawn from two universities in the south.

Of the northern group, all but two were asked by their teacher training mentors to modify their accents, while only four of those from the south were advised to modify their accents.

In the most shocking example, one trainee teacher from Leicester who described her accent as 'Midlands' was told that if she wanted to teach phonics, it would be best 'to go back to where she came from'. If she didn't, she was advised to use a teaching assistant to teach children certain sounds that differed from her own accent.

What is not clear is her ethnicity, but just imagine the outcry if the individual was anything other than white British and that was said to her.

Another trainee teacher from Manchester was told by the head teacher to 'be careful' regarding her accent. He then added, 'But you are from Eccles', and laughed.

To tell teachers in the classroom – an increasingly multi-cultural setting – to amend their accent smacks of double standards.

All the focus is on race, skin colour and ethnic background but it overlooks the fact that what truly identifies us is our accent.

Linguistic lecturer Dr Alexander Baratta said his research had found that accents most associated with the Home Counties were favoured by the teacher training profession, revealing a culture of 'linguistic prejudice' in a profession that would not tolerate prejudice based on race and religion.

'There is a respect and tolerance for diversity in society, yet accents do not seem to get this treatment – they are the last form of acceptable prejudice,' he said.

'We live in a society in which equality is championed and diversity is celebrated, certainly within the workplace, so why does it feel as if the teaching profession is completely discarding the unique richness that comes with regional accents?'

It is not the first time that this issue has raised its head.

In 2013 a Cumbrian teacher working in Berkshire was told to tone down her northern accent as a result of criticism by school inspectors, and this was then set by her school as one of her targets to improve performance.

True inclusivity is not just about embracing all creeds and colours but about accents too.

These findings have the hallmarks of the education system having gone stark raving mad and encouraging unhealthy, unreasonable, and unforgivable prejudice.

Let us hope that teachers will continue to take pride in their accent and origins, whatever their backgrounds.

To do anything other will lead to the demise of regional accents, harm the preservation and encouragement of them, and be damaging in terms of our wider culture and national/regional identities because in so many ways the diversity of culture, identity and inclusivity is shaped in the classroom.

It is not always the colour of our skin which defines us as individuals, but the dialect and inflections that come out of our mouths.

These accents – whether Norfolk, Somerset, Essex, Geordie, Midlands, Mancunian, Liverpudlian or broad Yorkshire tones – should be treasured, nurtured and preserved, and it is the next generation that is key to that.