The Black Country dialect is very different from Birmingham's. Pretend, for a moment, that you care. That's why Brummies call people like me (born in Wolverhampton, raised in Sedgley, although later schooled in Solihull, and suffering a Proustian rush every time I think about the nocturnal vista of flaming blast furnaces I saw when I sat on my nan's back step in Wednesbury) Yam Yams. We're so called because even – imagine! – Brummies think we can't speak proper. "Yam Yams" is a reference to the Black Country use of "Yow am" (or yow' m).

This matters because a primary school in Halesowen has banned pupils from using "gonna", "woz", "it wor me" and other purportedly yam-yammy locutions in the classroom in order to improve their grasp of standard English and, thereby, employability. Dudley North MP (and Yam Yam) Ian Austin backs the ban.

But there's more to Black Country dialect than these words, more even than Walsall-born Noddy Holder's orthographically challenged titles for Yam-Yammy Slade songs (Gudbuy T'Jane, Cum on Feel the Noize). There is a rich linguistic heritage that the Scottish novelist AL Kennedy identified: when I interviewed her about her book Day, which tells the story of an eponymous Lancaster bomber tail gunner who hailed from Wednesbury. "There's an enormous sense of humour in the way Black Country people speak," said Kennedy. "It's a very playful and very old language."

It is both of those things: "Ow bist" (How are you?), for example, is a contraction of the Middle English "How be-est thou", to which a reply might be "Bay too bah", which, like the French comme ci, comme ça, means "I'm not too bad". "Bay" means "am not" (as in "I bay gooin' ter tell yow agen"). "Yam Yams" say "aks" instead of "ask", "lickle" not "little", and when we play roughly we say we are "lungeous". "I ay sid 'er" means "I haven't seen her".

I remember my primary school teacher (who came from Lincolnshire) asking his class at Alder Coppice school in Sedgley what we meant by "saft". It was, we told him, a gently reproving combination of silly and daft. But we probably didn't put it quite like that.

Later my O-level history teacher Mr England insisted that Black Country dialect, unlike its upstart local rival, Brummie, was more closely related Middle English than any other regional dialect. That thought is picked up on the superb Sedgley Manor website, which gives a dictionary featuring such gems as "bunny-fire" (bonfire), "clack" (eg "Stop your clack!" ie "Shut up!"), "kaylied" (drunk), "waggin'" (bunking off school) and "lezzer" (not what you're thinking, but a meadow – derived from the Old English "leasowe"). If you stood in Sedgley Bull Ring now, what you'd hear spoken is a dialect nearer to Chaucerian English than any in use in England.

I'm also moved to tears as I write these words, recalling words that filled my childhood that I'll never speak again. I've been deracinated, standardised, made – linguistically at least – just that little bit less charming.

That fate awaits, perhaps, the pupils of Colley Lane school too. Doubtless they will gain in terms of employability and job security as their headteacher and MP hope, but they risk losing a cherishable and irreplaceable heritage as well.