Period Costume 101: First, dress the throat

I'm watching - hopelessly late, as usual - the BBC's adaptation of a novel that I love, Michel Faber's The Crimson Petal and the White. It's very good indeed, transporting us in fine style to the coexisting extremes of splendour and squalor of Victorian London. All except for one jarring incongruity - or, more specifically,  a glaring anachronism - in the period setting: the way the characters speak.

Chris O'Dowd and Amanda Hale (as William and Agnes Rackham) make do with a sort of Modern Sloane or Contemporary Rah. It works as far as it goes, inasmuch as it does convey a certain degree of toffitude to modern ears, but the problem is that the London rich didn't talk like that 50 years ago, let alone 140.

Just compare the Queen's accent when she was young with the one she uses today - they're as different as Scouse and Brummy. All that "It makes us viddy heppeh" business, or "often" sharing its first syllable with "awful"? The Queen doesn't talk like that any more, and I'm sure that Kate Middleton never has. But Agnes Rackham certainly should.

I had the same problem with Colin Firth and, to a lesser extent, Helena Bonham Carter in The King's Speech. You'd think a film that doesn't just touch on but is actually about what a historical character sounded like when they spoke would go to some trouble to get this stuff right, but no. I'm sorry, Colin, a cracking stammer face and all that, but King George VI didn't, in fact, sound just like Jeremy Clarkson when he talked. He sounded - or, rather, he syne-did, like Harry Enfield as Grayson in the Mr Cholmondley-Warner sketches.

But, getting back to Crimson Petal, the actors playing lower-class characters don't do much better, I'm afraid. Romola Garai's performance is fantastic, except for her voice. A Cockney woman making an effort to talk a notch or two "above her station" should sound like Irene Handl, not like Victoria Beckham. In the shifting sands of the wacky world of accents, whiny Generic Estuary is a very recent comer-in indeed - as out of place in a Victorian period piece as a mobile phone.

The best of the bunch, the cast member who seems to have paid the most attention to the way her character would have sounded, all laced up in her corsets and swathed in crinoline, is the one who had the most work to do of all of them. Although Gillian Anderson spent several years in London as a child, she's still an American. Yet she pretty much nails that clipped, oddly sing-song sound of someone trying to "posh up" a proper Old Cockney accent.