B ritish comedy has always liked a foreign voice to poke fun at, particularly one that hails from one of the former colonies; from Peter Sellers' "Indian" accent to the characters from 70s sitcoms such as Mind Your Language and Love Thy Neighbour. Meanwhile, Jim Davidson forged a career on the back of Chalky White, a particularly offensive imitation of a black Jamaican.

It's unlikely that we'll see Davidson on the box any time soon and equally unlikely that we'll see a Bangladeshi man waggling his head and saying "oh blimey" to raucous canned laughter.

In a complete volte face , what we laugh at now is the white man who tries to adopt a Jamaican (or Jafaican) accent in an attempt to appear cool or "street". E4's sitcom Phone Shop is a particularly good example of this new comedy trend.

Working in a mobile phone shop in Sutton are a cast of characters, including Jerwayne (who has a black London accent) and a motley crew who try to copy his patter. Lance, the shop's manager, is too old and Christopher too posh, but both try with varying degrees of success to master multicultural London English. Only Ashley, who has grown up with Jerwayne, is able to nail it, to devastating comic effect.

We can probably trace this trend back to the late 90s, when Sacha Baron Cohen's character Ali G first graced our screens. Much of the humour derived from the fact that Mr G was a British Muslim, adopting a Caribbean accent and swagger, played by a Jewish public school boy. Or take a more recent comic creation, "chav" Lee Nelson, played by comedian Simon Brodkin, who bowls around his council estate speaking perfect Jamaican-cockney.

If we see any kind of stereotype here, it is one not based on xenophobia but that stalwart of class distinction ? the way we speak. Comedians and writers who attended exclusive private schools and top universities, and who speak perfect RP, taking the rise out of the lower ranks, mocking those who they see as lacking intelligence and self-awareness and blindly copying a Caribbean patois.

However, the chances are that this Jafaican accent, which is like catnip to modern satirists, is not just an affectation, to try to make white boys sound cooler. Linguistic experts agree that this speech pattern is fast becoming the genuine sound of modern urban Britain, the native tongue of black, white and brown youth.

Let's face it, middle-class kids are less likely to grow up cheek by jowl with their immigrant neighbours and therefore less likely to adopt the cant of the Somali boy over the road or the Lithuanian kid they sit next to in maths.

This influence from other languages and dialects is not a new thing: it's been going on since at least the 18th century in the East End of London, when the first wave of economic migrants moved into the area.

So influential was the speech of French weavers on the indigenous dialect that these idiosyncrasies persist in 21st-century cockney. Dropping aitches and replacing "th" with "v" are hangovers from the French invasion. Who knows, maybe these Franco-cockney wideboys were satirised wildly by the ruling classes of the time. The question is "were they bovvered"?

The next impact on the cockney accent was from Ashkenazi Jews who brought a tradition of salt beef bagels and Yiddish to this part of London. Listen to an old East Ender, or even some of the older Essex diaspora, and not only might you hear a few Yiddish words peppering their speech but you'll also hear the nasal inflections and speech patterns of this ethnic group.

So is it any surprise that we now hear smatterings of Bengali and black Caribbean in the voice of east Londoners? Isn't it just a natural and fascinating development in the evolving story of the capital, rather than a wholesale pastiche from a group of white wannabes?

It's not just London that has picked up these patterns. Listen to a modern Leeds or Bradford accent and you can hear the influence of Pakistani English as clearly as the Yorkshire dialect of Heathcliff and Cathy. Meanwhile, the scouse accent owes as much to its Irish immigrant population as it does to traditional northern English.

Even parts of the West Country burr have picked up a Caribbean twang. This hybrid was brilliantly depicted by the Little Britain character Vicky Pollard ? the Bristol teenager who left school with six asbos ? played by Matt Lucas (who attended the same public school as Baron Cohen).

So if you're likely to say "D'ya get me", rather than "OK yah", or you prefer "ain't it tho?" to "don't you agree?" then you are rich pickings for modern comedy. The writers at the BBC are probably sizing you up for a sitcom right now ? Are You Being Served 2013, a gentle comedy about teenage drug dealers on a Dagenham sink estate.