c.2014 New York Times News Service

c.2014 New York Times News Service

The Duchess of Cambridge, the former Kate Middleton, wears a dress, and it sells out. The so-called Kate Effect has been noted for years.

But although plenty of attention has been paid to the dresses she has worn on the royal family’s tour in Australia and New Zealand (Prince William reportedly said that she looked “like a banana” when she wore a yellow Roksanda Ilincic dress in Sydney), she’s not the only one in the family. On the trip, the royal family has introduced a new teeny style icon: Prince George, who, as a 9-month-old, is already having a big effect on some fashion businesses.

“Every mother, especially the British ones, dream of dressing their children like the royal baby,” said Christine Innamorato, the creative director of Bonpoint, an upscale children’s clothier. “He might only be 9 months old, but Prince George is already a trendsetter, just like his mother.”

Take Rachel Riley, a London-based children’s label that is sold at stores in London, on Madison Avenue and at Barneys and Bergdorf Goodman. Her designs have been all over little Prince George on the trip.

There were the sailboat-smocked dungarees at a play date in New Zealand; the blue cardigan he wore in his mother’s arms as they left a plane in Canberra; and the Easter outfit, a striped polo and navy shorts, he wore while examining a bilby (the Aussies’ version of the Easter bunny, apparently) at the zoo.

Riley, who was unaware that her clothes would be worn by the young prince, feels as if she hit the jackpot.

“It’s life-changing,” she said, on the phone from London. “I love to dress my own children, and I love to dress our customers’ children. But if you asked me if there was one child I’d like to dress, it would be the next heir to the throne.”

The business has been swift. The sailboat dungarees sold out online “in a few hours, maybe less than that,” she said. His later outfits (the shorts, the polo shirt, the cardigan, which range from $75 to $99) are still available but are not likely to last long. Reorders will be made, she said.

“We’ve had celebrity customers before, and we’ve also had royal customers before, but I don’t think we’ve ever had anyone before quite as high profile as Prince George,” she said. “Being on such a high-profile baby is very good for business.”

She is not alone. After Prince George wore an Annafie sailboat romper, the label received “a lot of orders for more stock,” said Elisabeth von Kospoth, the owner, who encouraged a reporter to consider “similar models” of the romper.

The shoe company Early Days (“Caring for baby’s feet since 1952”), in Leicester, in central England, was unprepared after Prince George was spotted in its prewalkers. The Early Days website warns that because of unprecedented demand, online sales have been shut down.

Paul Bolton, an owner, said that the shoes sold out online within two hours of the baby’s appearance in them and that the demand had been “far outstripping our production capacity.”

“If the demand does continue, we will seriously consider expansion,” Bolton wrote in an email.

Those shoes sell for less than 30 pounds (about $50), and, in general, almost all of Prince George’s clothes are in the affordable range. The royal family is not jumping into the superluxe designer game, in which a Dolce & Gabbana toddler’s sequin dress sells for $1,375 and a Burberry trench goes for more than $800.

And the duchess may have had appreciated the flexibility that Riley’s clothes seem to provide. She reportedly said that Prince George has grown “an extra fat roll” on the trip, and Riley, a former model, has said that her classic clothes for kids should fit — yes, designers talk like this for tots, too — “children’s bodies.”

Prince George is not the only baby fashion icon, of course. Beyoncé and Jay Z’s daughter, Blue Ivy, gave a bump in business at the Catimini store in New York after she was spotted in its silver coat this year.

“They’ll see the jacket and start calling and coming in,” said Jennifer Grey, the store’s manager. “It definitely boosts sales.”

Riley said her business has a stronger track record with girls (“It’s easier and more fun to dress girls up,” she said), but Prince George may give boy’s clothes a6 lift.

“We’ve always been well known for our girls’ clothes,” she said, “and suddenly the boys are overtaking the girls.”