Viktor Horsting and Rolf Snoeren have been dubbed the first great conceptualists of twenty-first century fashion. Their work is always considered, always thought-out - but unlike so many others, even in the world of fashion, it is designed to function foremost on an aesthetic level. The concept is never obtuse or laboured - it's instant, it's visual, it often leans towards the pun. There's never a danger you won't get it.

Most consistent is Viktor & Rolf's play with scale and trickery of the eye. In the mid-nineties, they crafted a couture collection on Barbies, and at the end of the decade scaled up their garments to pile intricately on top of one another like layers of a Matryoshka doll. It's notable that they started creating clothing as haute couture - rendered a costly loss-leader by the end of the twentieth century, more advertising than actual clothing. This was fashion created to be photographed and filmed, created to be read as a flat image rather than an actual garment - the trick with the Barbie-scale couture was that it read as full-size in the photographic image. The medium suits the message: after all, haute couture by its very nature will never hang in a boutique, strictly made to measure for individual clientele and seen by the vast majority as image rather than reality.

Viktor & Rolf moved into the ready-to-wear arena ten years ago to the season, but this bag carries over the conceits of their couture. It is titled 'Perspective' and it does exactly what it says on the tin, tricking the eye by sharply sloping from left to right, with elements set on an incline and hence appearing to recede into the far distance. No design detail has been spared - the bag bulges at the back, leaping into our line of vision, with even the two halves of the faceted clasp scaled to retreat.

The reason Viktor & Rolf's bag is quite so arresting is because its form is familiar. In the same way that their twists on clothing rely on classics such as the white shirt, the little black dress and the Le Smoking tuxedo, in this instance they have chosen to distort a traditional black patent frame bag. The double speak in this item is that the shape is not only recognisable but, for a split second, our eye is fooled - the bag reads as perfectly normal from one angle, but suddenly skews as the angle changes, transforming from mundane into extraordinary.

The work of Viktor & Rolf has often been branded as heavy-duty conceptual, but certainly in this instance it is playful rather than po-faced, and relies more on the graphic than the intellectual. It puts me in mind of M.C. Escher - a fellow Dutchman - and his 'Impossible Realities', appearing at first glance genuine and tangible, but under scrutiny quickly twisting into fantasy. Viktor & Rolf are not only his countrymen, but undoubtedly his fashion counterparts.