Kate Middleton effect quadruples Seraphine profit

“We were the only specialist maternity retailers that were seen to be dressing her during her pregnancy, which put us on the map.

“The fuchsia Jolene dress was the really big cherry on the cake but we benefited from the overall message about who we were to the Duchess of Cambridge", she said.

Ms Oliver said that the Duchess of Cambridge's style choices made her a role model as well as a style icon.

“She was wearing a maternity brand post pregnancy and she was saying to the world, ‘I’m a real woman, I’m not jumping back into tiny fitted clothes’. On top of her looking great, her message was such a good one", she said.

Seraphine has three London stores and is planning to open a further two UK locations this year, as well as a New York store.

The company said it plans to capitalise on the publicity and hopes to grow a further 60pc in the next 12 months, with revenues predicted to reach £13m by March 2015.

Seraphine sells most of its products online, with 65pc of turnover coming from website sales.

The “Kate effect” has led to increased sales from several British brands, including Reiss, Whistles, and LK Bennett, with individual items often selling out within hours once worn by the Duchess of Cambridge.

Jenny Packham’s website crashed after Kate Middleton stepped out in a polka-dot dress from the designer after the birth of Prince George, and LK Bennett decided to expand its presence in the United States after the Duchess of Cambridge’s fashion choices raised the brand’s profile.

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