Mary-Kate and Ashley Olsen's fashion label The Row is successful because it is "timeless and directional".

The 24-year-old twins - who have recently been nominated for Best Newcomer at the forthcoming CFDA (Council of Fashion Designers of America) awards - have seen their upmarket range go from strength to strength since its launch, which Averyl Oates, buying director for Harvey Nichols, who stock the range, believes is due to its enduring appeal.

She said: "The label carries timeless generational appeal while still remaining directional.

"Mary-Kate and Ashley recently achieved their ambition of dressing Michelle Obama. Lauren Hutton has also modelled for the brand and I think the ageless appeal lies with the fact that the collection has a crystal-clear DNA."

Mary-Kate and Ashley - who had a clothing range in Walmart at the age of 10 and launched their first own label, Elizabeth and James, in 2007 - have also done well with The Row because they knew how The Fashion industry worked.

Averyl added: "We exclusively launched The Row with a dinner for the Olsens back in 2007. Even though it was a new brand, it was an immediate hit. And even then, the girls were not new to the commercial aspect of business."