Kate Middleton’s TOPSHOP dress she wore today at the Warner Bros film studios quickly became a sellout.

The dress was available to buy from TOPSHOP’s online store this morning, but within an hour of Kate Middleton stepping out in the polka dot garment it was out of stock.

Bargain hunting fashionistas rushed to buy the £38 ($59) dress that fits the Duchess of Cambridge even though she’s currently six months pregnant.

Kate Middleton, 31, teamed the black and white dress with a black Ralph Lauren jacket as she toured the Warner Bros film studios with Princes William and Harry.

Kate Middleton’s TOPSHOP dress she wore today at the Warner Bros film studios quickly became a sellout

She has long been a fan of TOPSHOP and has been seen in clothes from the British brand on numerous previous occasions.

Just last month, Kate Middleton wore a £46 ($72) black shift dress from the store with a white Peter Pan collar as she attended the headquarters of Child Bereavement UK with Prince William.

Kate Middleton, who is due to give birth in July, was spotted browsing the rails of one of the store’s London branches at the beginning of March.

On that occasion, the duchess was rumored to have bought a short floral print dress called “Deirdre” that she has yet to be seen wearing in public.

Today isn’t the first time Kate Middleton has caused a spike in sales at TOPSHOP. Back in 2007, long before she was the Duchess, she was still making her mark as a style icon.

When she was pictured out in a black and white patterned tunic from the store it flew off the shelves.

Kate Middleton’s sister, Pippa, is well-known for sharing her sense of style and she’s also regularly seen in TOPSHOP garments. While another high profile fan of the brand is Andy Murray’s girlfriend Kim Sears.

But TOPSHOP isn’t the only High Street store Kate Middleton champions. She also regularly wears clothes from Reiss, LK Bennett and Zara.