It's lucky that the good folk at Paddy Power restrict their odds-laying to basic sartorial stuff such as what colour hat the Queen will wear to Ascot, because what kind of a fool would bet on the success or otherwise of an actual trend? Take this whole pyjama thing. When printed silky trousers and matching shirts with a distinctly bedtime look first started appearing on the catwalks six months ago on gawky young models, the most generous of bookmakers would have given you odds of 500-1 that the look would take off in real life. But now, retailers at the commercial end of trend-watching will tell you that the odds on the PJ look taking off are considerably shorter.
It was Jane Shepherdson, the faultless dresser and CEO of Whistles, who broke the news to me. At a press preview of the brand's collection for next autumn I asked her what this season's Carrie skirt was. That, by the way, is not inquiry related to Claire Danes's lamentable wardrobe in Homeland. The Whistles Carrie skirt was a knife-pleated chiffon number that, difficult as it was to wear, became a massive hit for the chain last summer. "Our wisteria print pyjamas," was Shepherdson's decisive answer. Really? Shepherdson explained that yes – there weren't many sizes left and that a whole range of women had bought them and that they had proved to be the "age-blind" hit of the season. "We've sold the top and matching trousers to 20-year-old fashion students and to a very chic 60-year-old woman who wanted something for a wedding that was cool, effortless and different," she said.
It's not just Whistles that has noticed the pyjama trend. During the most recent fashion collaboration storm at H&M, Marni's pyjama shorts set was a clear hit. It was suitably tricky to wear together yet delightful as separates. At Topshop, head of buying Madelaine Evans reports that the trend is a "key look" and that the brand has experienced a "particularly strong reaction to the soft, printed pyjama trouser". Presumably the strong reaction is more positive than the reaction of our very own fashion sage Hadley Freeman, who decried the trend as one that only the cast of The Golden Girls could rock with any dignity. Meanwhile at the designer end of the spectrum, matchesfashion.com only has Stella McCartney's paisley-print pyjama look (the one she wore to the launch of the Team GB Kit) available in a teeny-tiny size. That suggests that several grownup women willing to part with £430 for the trousers and £435 for the matching blouse have already converted to the high-end Andy Pandy look.
So how did this happen? Surely this can't be down to the celebrity factor? Yes, Tilda Swinton and Sofia Coppola were both early adopters, looking respectively fabulous in a cream silk matching set and a Louis Vuitton printed number (with coordinating slippers) but most reasonable women would dismiss this with a lovely-but-not-my-life shrug. Similarly, McCartney and Rihanna have both recently looked excellent in McCartney's own interpretation. However, the designer has a clear commercial interest in making them look convincing on thirtysomething women and the singer favours see-through tops and trucker caps – so she can't be trusted in these matters.
The likely reason for the trend becoming popular is that it is universally flattering. I'd add to Shepherdson's observation that the style is shape-blind as well as age-blind. My own Zara version with their elasticated waistband and baggy top are proving to be just about the only current look that works with a five-month pregnancy bump when you are trying to look smart.
As with any eyebrow-raising trend, how you wear it is key. I'd say that making the pyjama look work boils down to three things: earrings, heels and a confident posture. Swerve anything that looks too cosy – so avoid bobbly cardis and wear with a tailored jacket. Similarly, flip-flops and an unsure expression kill the vibe. Natalie Kingham, Matches' international womenswear buyer, suggests that we "think silk separates". She advises trying "PJ pants with a white T-shirt or classic grey sweatshirt and wedges, or a printed PJ shirt teamed with your jeans, which makes it feel effortless and modern. Shepherdson agrees that the look is timeless when you wear the pieces as separates and talks about battered jeans, heeled sandals and simple grey T-shirts.
For pyjama converts, there is more good news. Topshop is expecting sets in calypso florals, paisley and geometric prints by the end of the month and judging by high street previews for next autumn, the look is no flash in the pan. At Whistles, pyjamas will morph into posh tracksuit bottoms with drawstring waists and colour blocking. And let's face it: if a trend can last two seasons, looks good and is comfy around the waistband then that is exactly what you'd call a safe bet, isn't it?
guardian.co.uk © Guardian News and Media 2012