Tony Thorne: Rhyming slang is brown bread? Don't you Adam and Eve it...

The Museum of London announced last week that Cockney rhyming slang is dying out, no longer understood by a majority of Londoners, let alone people elsewhere. The museum's research suggests that youth slang, rap and hip-hop lyrics, and textspeak have ousted what they call the "traditional dialect" of working-class Londoners. A majority of the 2,000 people who took part in their survey failed to recognise phrases like "brown bread" for "dead" and hadn't heard "apples and pears" used for "stairs" in the past six months. Fifty per cent, on the other hand, had heard the words "wicked" and "innit", while 40 per cent were familiar with the phrases "OMG" and "LOL"– the abbreviations for "oh my God" and "laugh out loud" used in texting.

Intriguingly, two-thirds of those questioned still think rhyming slang is a key part of Londoners' identity, and a third said they would be sad if it disappeared for good. I'd like to reassure them that, although it may be going through something of a linguistic recession, it's far too soon to toll the bell for rhyming slang. In several interesting ways the museum has got it wrong.

Nobody actually talks in "Cockney dialect" any more, and strictly speaking they probably never did. In connection with a style of speech the word was only recorded in 1859 and after that was used to refer to a distinctive accent, a few colourful turns of phrase and a feisty, jaunty sense of humour. The habit of using rhymes to create slang probably developed in the 19th century, too, but like other quirks of speech which don't get written down until years later, its origins are quite obscure. Historians assume that street traders, hucksters and hustlers invented the rhymes as a secret language to hide their activities from outsiders and the authorities, but this, too is unproven. If stallholders call their customers "Billies" (from Billy Bunter – punter) or refer to the till as the "Benny Hill" or "Buffalo Bill" they are using harmless nicknames not sinister code words. What is sure is that by the 1950s many working-class Londoners, fond of a bit of wordplay, were trading these phrases among themselves, often leaving off the rhyming part so that "taking the mickey" is trimmed from the original "Mickey Bliss", "telling porkies" is cut down from "porky pies", and "boat race" for "face" becomes "nice boat, shame about the fried eggs".

By the 1970s, non-Cockneys were getting in on "lemon meringue": musicians picked up the lingo from their roadies and electricians, advertising executives and journalists from messengers and drivers, Mockneys everywhere from TV shows like The Sweeney and Minder. From the 1980s, students, too, took up the cause, updating the cultural references with terms such as "Ayrton Senna" for "tenner", "Melvin Bragg" for"fag" (and sometimes another rhyme, starting with sh) or "chicken jalfrezi" for "crazy". In college circles, the old "Turkish bath" or "bubble bath" for "having a laugh" was replaced by "bobble (hat and scarf)"; trainers became '"Claire Rayners" or "Claires" and "Tony Blairs" were the flared trousers flapping above their ankles. "Posh'n'Becks" could be sex or the decks – turntables – used by DJs. Typical terms include "furry muff" for "fair enough"; oriental students are "ornamentals", cash dispensers "drink-links". In the same spirit, a drink of Stella (Artois lager) has mutated through "Yuri" (Geller) and "Nelson" (Mandela) to "Paul" (Weller). Conversations end with "baked potato" – "see you later".

Language evolves and adapts to the times, and rhyming slang is no exception. That's why the hoary old expressions chosen by the Museum of London – "dog and bone" (phone), "trouble and strife" (wife), sound as charmingly and hopelessly dated as Donald McGill postcards: I somehow doubt, too, that anyone ever really called their cupboard "Mother Hubbard" or used "custard and jelly" for "telly". Listen out today and you do stand a chance of coming across "Andy" (McNab) for a kebab, "Johnny" (Vaughan) for yawn – and porn. "Britney" is the universal code for beer. Being on the dole used to be "on the rock'n'roll", now it's "on the Cheryl Cole".

The other point that the survey misses is that rhyming slang is not necessarily meant to be understood, at least not immediately or by everyone. It isn't a shared dialect, it's an ever-changing word game, improvising references and puns, and challenging listeners to make sense of them. The technique now belongs to everybody and anybody, and lots of current rhyming slang occurs in the home, with family members competing to declare that they "haven't a Scooby" (Doo – clue), drying themselves not with a towel but a "Simon" (Cowell) before putting on their "Baracks" (pyjamas, of course).

There are some indicators, though, that the Museum of London's fears for the future of rhyming slang may be justified. It's certainly the case that at the moment it isn't at the forefront of cool. Members of the white working class, if that term still means anything – "white-van man", taxi-drivers, builders and decorators, sparks and chippies – may still invent new rhymes, but white working-class pop culture is far from fashionable. Chavdom has given it a bad name, and the heyday of the "geezer chic" of London gangster movies such as Lock, Stock and Two Smoking Barrels is a thing of the fast-receding past.

The cliques who occupy the high ground of cool these days, at least in their own minds, are the hipsters of Shoreditch and Hoxton, the patois-speaking street gangs and their imitators, Lady Gaga and Nicky Minaj-fixated teens, and their gloomy emo counterparts. These groups all have one thing in common: they completely lack humour, and rhyming slang is above all a joke, a feature of a mind-set for which cheerful irony, back-and-forth banter and self-mockery are mainstays.

Texting abbreviations, fashionista jargon and pseudo-Afro-Caribbean "Jafaican" may be in the ascendant now, but will make way for other language fads in due course. Maybe when and if the terminally hip and the genuinely pubescent grow up, stop posing, and acquire a sense of fun, they too will embrace the enduring rhyming game.

Multi-ethnicity and diversity is another challenge to London's former folk culture. Up to now, the rhyming technique has been recorded only among native speakers of English. So it has also flourished in Australia (where "Noah's arks" are sharks) and there are a few examples from the United States ("Skin and blister" for "sister" is said to be North American) – so we might assume that members of New Britain's multicultural population whose "heritage language" is not English will be immune to rhyming slang or incapable of mastering it. I live in hope, nevertheless.

There is no such thing as a native speaker nowadays; many people, especially in the cities, are bi- or multilingual, and adept at "code-switching" between languages, even in mid-sentence. Why shouldn't British Asians, Somalis and Poles begin to experiment in the year of the Olympics with this special form of verbal gymnastics? I haven't any hard evidence yet that they are, but I'm listening carefully.

Tony Thorne, Language and Innovation Consultant at King's College London, oversees the Archive of Slang and New Language. Readers are invited to send contributions or comments to tony.thorne@kcl.ac.uk