Who knew that the inexhaustible store-box of Sadie Frost's talents extends to being bilingual, and that her second language is a secret one known to very few?

There is no celebrity as unfairly maligned as Sadie, who has somehow come to be an emblem of unearnt fame. Ricky Gervais's character in Extras said, for example, when asked what she actually does, "She's friends with people".

Which is just typical mischief-making. Because actually, Ricky, she is also the ex-wife not just of Jude Law but also Gary Kemp, she designs things and she is in a play: Touched... Like a Virgin at London's Soho Theatre. Also, she is probably the first person in north London to ever wear an Ugg boot and she is a cornerstone of the Primrose Hill Set, in which, yes, yes, she is friends with people such as Kate Moss. It is as a linguist, however, that she deserves most respect. Sadie is fluent in Uvaguv, which is spoken almost exclusively by witches, Freemasons and Sadie Frost.

It looks an easily acquired language compared with Sanskrit, Mandarin and Welsh, since it requires no more than the ability to insert the syllables 'uva' and 'guv' into English words. Its purpose is to baffle non-Uvaguvaphones, while at the same time making the speaker feel like a member of a very select private club – as if the early Ugg-boot-wearing, Primrose Hill thing weren't enough.

Without a textbook to fall back on, we must look to a real-life episode; the time Sadie's two-year-old daughter accidentally ingested a pill at Soho House in London. Here goes: Sadie – "Excuse me, but could you call an uva-am-guv-alance? Only one of my uva-child-guv-ren has swall-uva-ow-guv-ed an uva-ecsta-guv-y uva-tab-guv-let..." In using the language, Sadie will not merely have made herself sound clever and mysterious, she will nimbly have avoided alarming fellow parents at the celebrated Class A children's party into thinking their own offspring had been taking ecstasy.

She may have also used Uvaguv again later that day when she had the tricky task of ringing Iris's father, Jude Law, another fluent speaker, who was away filming in the US. Whether she reverted to plain English, if only for brevity, to break the news is not known. Nor is the language he used to break news of a real-life episode of his own. "Uva-dar-guv-ling, I'm so uva-sor-guv-ry, but I've been uva-bang-guv-ing the uva-nan-guv-ny and the uva-tab-guv-loids are on the case!"