Accenting the positive on screen

Meryl Streep can expect her vocal tones to come under close scrutiny when she plays Margaret Thatcher, but then, unlike many of her screen colleagues, she has always excelled at accents.

So Meryl Streep is to play Margaret Thatcher in a new film. One wonders if she knows what she's letting herself in for. After all, the responsibility of taking on the famous grocer's daughter from the none-more-English market town of Grantham has been given to someone from New Jersey. There will undoubtably be a point where the actress who bounced her way through Mamma Mia so entertainingly will have to take a deep breath. And, masking that East Coast drawl, she'll have to say in the former British prime minister's inimitable, iron-clad accent born of so many elocution lessons: "Defeat? I do not recognise the meaning of the word." Rather than gasping at the dramatic pathos, an entire country will be looking at each other and saying: "Has she got the accent right?"

Make no mistake, when it comes to the way actors deliver their lines, the British are obsessed with authenticity. No one else on the planet thought to question Russell Crowe's curious brogue in Robin Hood, which somehow moved from Ireland to Yorkshire, to Australia and finally to where it should historically have been: the flat East Midlands vowels of Nottinghamshire. But when the BBC presenter Mark Lawson dared to raise it on his radio show, Crowe exploded. "You've got dead ears, mate," he growled. "You've seriously got dead ears if you think that's an Irish accent."

Of course, if Lawson had wanted Robin Hood to be completely historically accurate, the merry men would have been speaking in a version of old English incomprehensible to everyone but linguistics scholars. So why was there so much fuss? Probably because it seemed so lazy: in a multimillion-dollar movie with a big star playing an English legend, surely a voice coach could have imparted some continuity. Even if the accent wasn't geographically accurate, at least it should have been consistent.

Watching actors grapple with accents they can't master - English or not - is often great fun. But it can also be tortuous to the point of ruining the films they're in. Defiance, starring Daniel Craig, was a remarkably well-judged action film from 2008: the true-life tale of the Second World War Jewish resistance fighters encamped in the Belarusian forests. Obviously it needed star-power to help it into the cinemas, and who better than the incumbent James Bond to provide it? But to see him struggle with a weird, broken-English accent - intended perhaps to suggest that he was from Eastern Europe - was completely off-putting. He battled with it as manfully as he did the evil Nazis, but eventually lost. Some of the worst accents committed to celluloid are American attempts at English - Don Cheadle in the Oceans series, Dick Van Dyke in Mary Poppins to name but two - but no nationality truly escapes mangled voices. The television series Flash Forward was embarrassingly dumped mid-season, collapsing under the weight of its slightly strange premise. But it didn't help that the main protagonist, Joseph Fiennes, was so bamboozled by the overbearing seriousness of his role as an FBI agent that he ended up delivering every line as if he were voicing a trailer.

Renée Zellweger was rightly praised for her English accent in Bridget Jones, but her American South effort in Cold Mountain was the stuff of pantomime. And the less said about Jon Voight's Spanish attempt in Anaconda, the better. There are people, of course, who make taking on different accents sound easy. It's said that most Americans didn't realise that Hugh Laurie, the star of House, was a comic stalwart from England. The brilliance of Dominic West's turn as a Baltimore detective in The Wire was such that few British fans of the show, let alone American ones, realise he comes from Sheffield in the UK.

But sadly, those are the exception rather than the rule. There is an easy solution: ask actors to speak in the same voice they'd use to order a coffee or speak to their children. It has its drawbacks - it means that English actors would have to be in English films, but that's no bad thing. Surely there is someone capable of playing Thatcher who was born in the same country as the woman known as the Iron Lady.

Of course, it'll never happen. And in the end, the prospect of Streep playing Thatcher shouldn't give Britons too many sleepless nights: she's succeeded in being authentically Polish in Sophie's Choice, Danish in Out of Africa, Australian in A Cry in the Dark and English in both The French Lieutenant's Woman and Plenty. The secret of her success? She works - hard - at her voices. Something lesser actors and actresses would do well to emulate.