If behind every successful man is a woman, then according to ‘The September Issue’ behind every successful woman is another woman. The fashion curious may eagerly queue up to discover more about ‘The Devil Wears Prada’ inspiration, American Vogue’s boss Anna Wintour, but will leave intrigued by her office wife.

The fly-on-the-wall documentary follows Wintour and her editorial team as they prepare the most important Vogue, the eponymous September issue, which sets the tone for the next fashion year. Filmed in 2007, the focus is on the most successful issue yet, the 13m-selling Sienna Miller cover.

Although RJ Cutler’s film is not a biopic of Wintour’s life, over the past 21 years the Editor-in-Chief and her Vogue have become inextricably linked. Yet she doesn't emerge as the star, rather it’s the magazine’s Creative Director Grace Coddington and the relationship between the two that make this the successful documentary it has become. That and the ability of ‘An Inconvenient Truth’s cinematographer Bob Richmann to entice the notoriously closed shop to open up - earning him a Sundance Festival award for his efforts.

While the trademark bobbed, shaded and coiffed Wintour may be the business brains behind the brand, romantic, unkempt Coddington is the behind-the-scenes creative genius. They respect each other and their various roles within the company, where they both began working on the same day in 1988. They are certainly both aware as they flirt with their golden years that they are striving in a world which constantly looks to the future. They need each other but with Wintour as the overall boss, it’s a bitter pill for Coddington to have to swallow when her work ends up on the editing room floor. She may look like an aged Florence without the Machine, but 68-year-old Coddington is a former Vogue model, having graced the cover of the fashion bible in the 60s/70s before a car accident swerved her career in the current direction.

Described as a "quiet powerhouse" by the New York Times, she's one of Wintour’s rare worthy adversaries, fighting for what she believes in, which makes for wonderful viewing. As are the scenes where photo-shoots go wrong and few are spared Wintour's glacial glare, even cover-girl Miller and her "unruly" hair and teeth get a dressing down, albeit when she's out of earshot (until she sees the film that is!).

She may be frosty and autocratic, but as expected there’s more to Wintour than the ice-queen myths, perhaps her aim in the film is to dispel them. She comes across as tough yet professional, tactless yet efficient, a ruthless decision maker, a talented editor who is rarely wrong. But warm? Definitely not, that 'Devil wears Prada' tag is undeniably hers. We learn little about her private life, just a few family facts and her obvious love for her children, but no glimpse of hubby or mention of her mother.

Pity the film wasn’t released ahead of the actual September issue hitting the shelves, as excited film fans would no doubt have driven the movie buzz, never mind circulation figures. Not a very Wintour move, given that ad content is down a third on last year. However, while lacking critique from Wintour’s bosses (Condé Nast) and competitors alike, ‘The September Issue’ is an unprecedented, un-airbrushed snapshot into the inner workings of the magazine - the biggest and best ad Vogue could ever design.

Taragh Loughrey-Grant