Meghan Markle was left red-faced after it was revealed that her American Riviera Orchard brand name is being used for a very different brand of adult colouring books.

Meghan Markle has suffered an embarrassing blunder with her new brand. (Image: GETTY)Meghan Markle has been caught in a blunder as it turns out her lifestyle brand name, American Riviera Orchard, is already being used by another company to hawk adult colouring books online.

The Duchess of Sussex, who unveiled her new business endeavour in March, aimed to launch a line featuring preserves, jams, nut butter, homeware, home fragrances, pet products, and cookware.

However, The Independent reports that an enigmatic seller in the US has set up a Shopify page offering colouring books for adults, including one titled “Working Class Royalty”, with prices ranging from £8 to £16. Currently, one of the colouring books is sold out, and there are also two financial planners on offer, with prices varying based on size.

Celebrity PR guru Jane Owen spoke to The Mirror, slamming Meghan’s team for not being thorough with their “overall brand strategy” and pinpointing this oversight as the cause of the embarrassing mix-up.

“I think this is an embarrassment to the people running her company for sure. They should have been more careful to tie up all uses of the name legally so this could have been avoided,” she said.

Jane continued: “It shows a glaring lack of overall brand strategy which should have encompassed everything and predicted this kind of thing happening and prevented it.

“What I recommend they do is take every legal action to get this person to cease and desist. Then they buy up everything remotely connected to the name and put their marketing and advertising into overdrive to compensate for this and do damage control on the brand name.”

Despite the Shopify page declaring no connection to Meghan’s brand, the website description implies an anti-monarchy stance, suggesting that the name could be being used to protest against the Royal Family.

Meghan Markle, Duchess of Sussex, looks on as she attends a Sit Out with Prince Harry. (Image: Getty Images)

A blog post on the Shopify page dismisses royal titles as having “no significance” and states their “RoyalWealth ReignTM line was established to recognise and celebrate the working class who are the true heart of our country.”

The US-based brand further stated: “In America, we do not recognize a royal title by someone’s name. In America, we believe ALL are created EQUAL.”

Another post adds: “Americans reject and don’t care about Royal Titles like Prince, Princess and Duchess.”