Gove has said the unsayable, but I do believe that he is right this time. There are children in dd's class whose working class accent is so broad that they practically need speech and language therapy. There is nothing wrong with regional accents, but everything wrong with lazy speech where children fail to pronounce their vowels property. I can see poor pronouncation entering dd's speech. For example she misspelt water as "worer" . It is going to be hard for children with incomprendible thick accents to get middle class jobs where good communication skills are essential.
I completely agree with this. (although I think it's unfair to pick on vowel sounds specifically - they vary hugely from region to region, and it's perfectly possible to articulate yourself extremely clearly with ugly vowels.) 
People mistake a requirement to 'speak properly' as being asked to shed all traces of regional accent. It does not mean that at all - it just means that if you are not capable of enunciating clearly and do not have a decent grasp of basic grammar then it will be very difficult to learn spell, to be understood clearly outside of your own social environment, or (most importantly) to reach the required standard of written and spoken English that enables you to thrive and be taken seriously in a professional environment.
If you get a poker up your arse over this and you cannot accept that there is ahuge middle ground between asking someone to drop the 'Vicki Pollard' and demanding that they mimic Kirstie Allsopp then you are being very blinkered and obstructive.
Sometimes very working class people (especially young men IME) do themselves no favours. In bloody-minded determination to be true to their roots they often swagger, grunt, mumble, display defensive or aggressive body language, and basically just refuse to scrub up a bit and learn the art of 'best foot forward' and making a good impression.
There is a culture of stubborn 'learned helplessness' that can affect everything from dreadful grammar, poorly written CVs and letters of introduction, inappropriate attire for a business environment, appearing rude or gauche because of a lack of awareness of basic etiquette, to (at the extreme end) disgusting table manners.
Even a dogged attachment to casual vernacular speech and the reluctance to use 'big words' due to either a lack of confidence, or a fear of acting 'posh and poncey' could result in someone appearing inarticulate, one dimensional and not very bright.
That may not be the case at all, of course, but it is the impression it might give.
If you listen to working class and lower MC young teenagers chatting you will notice they often use descriptions like clever brainy posh snob goody-goody and nerd as interchangeable. There seems to be a very misguided but implicit understanding among many of them (given their often limited exposure to people they perceive as 'posh') that you cannot be any of those things without automatically being the other.
That attitude needs to change, for several reasons, but not least because it creates real barriers in encouraging many young WC people to aspire both at school and beyond. They start to believe their own nonsense - that only 'snobby' or 'posh' people are clever, self-disciplined and well-behaved, and to aspire to any of those things is to be 'snobby.'
That's fine if they are happy to continue the status quo by becoming skilled or unskilled manual workers, blue collar workers etc, and there is certainly no shame in any of that at all.
But in order to aim for something with more scope for advancement and financial and social mobility they may need to brush up on their personal presentation skills. And just accept that making an effort to appear more appealing to people in authority is, annoyingly, the most cast-iron route to getting on in life.
And if they are not prepared to do that, out of some warped sense of disloyalty to their class then they can expect to stay exactly where they are.