Forget the Spice Girls; with 30 million CD sales from three albums, the Dixie Chicks are the biggest-selling female group in history. What’s more, they’re not remotely posh, sporty or scary.

In fact, the Chicks (Natalie Maines and sisters Martie Maguire and Emily Robison) come across as three ego-free Southern belles whose success is based purely on talent, principles and a commitment to music matched only by that to their families.

But after taking the country music world by the scruff of its (reddish) neck, Maines committed a cardinal sin: she dissed the President in public. On foreign soil, too.

With the war in Iraq grinding into its second year, Maines quietly aired her frustration on a London stage: “We’re ashamed that the President of America is from Texas.”

It got a big ol’ cheer from the country lovers of Shepherds Bush, but when the folks back home got wind of it - woowee, did they ever get their bootlace ties in a twist.

The girls returned to find mountains of their CDs being crushed under foot and terribly spelt anti-Chicks slogans wherever they looked. They were boycotted by sponsors and radio stations alike. Redneck crooner Tony Keith wrote nasty songs about them.

Despite several apologies, a few T-shirts of their own (‘FUTK’), a nude cover for Entertainment Weekly and the commendable efforts of their British manager Simon Renshaw, the backlash raged on.

Most Americans, it seems, are all for free speech - as long as they don’t hear anything they disagree with. So, not being kiss-ass types, the girls simply got on with making music and putting on shows for the fans that stayed loyal.

Sticking close without intruding, the filmmakers paint an intimate and inspirational portrait. We’re on hand for the birth of Emily’s twins, yet while Martie breaks down in tears, even a death threat is not enough to keep the irrepressible Natalie quiet for long.

Married to Adrian Pasdar, the flying politician of Heroes, Natalie is something of a hero herself. Her defiant ditty ‘Not Ready To Make Nice’ is the standout track on Taking The Long Way, the Chicks' first album since the brown stuff hit the air circulation device.

Makin’ nice or no, you can bet your bottom dollar that Shut Up & Sing will get plenty more folks whistling Dixie.

Elliott Noble