Prince Harry and Meghan Markle's wedding is already proving to be a cash bonanza for some UK firms
  • Local businesses in Windsor say the town is nearing full capacity ahead of Prince Harry and Meghan Markle's wedding.

  • Both premium marketers and budget retailers offer royal-theme products.

  • The royal wedding is unlikely to bring much of a boost to the wider U.K. economy.

Running a bakery in a small, English town on the outskirts of London usually brings its fair share of quiet days.

But, for Edward Durkin's family-owned bakery, May 19 could well be the busiest day in its 100-year history.

Four generations on since his family first opened Heidi Bakery in a shopping mall opposite England's Windsor Castle in 1918, Durkin is in a prime position to take advantage of the marriage of Prince Harry and Meghan Markle.

"This is the biggest event in our bakery's history and we are taking full advantage of the day," Durkin told CNBC.

Local businesses in Windsor are already reaping the rewards that an influx of tourists — especially those from the U.S. — will bring to the Berkshire town.

"I don't think it's ever been as sustained and drawn as much international attention as much as this," Durkin said. "We remember William's and Kate's 2011 wedding, but that was in London. The real key is having the event in Windsor."

Location isn't the only advantage. Heidi Bakery has held a royal warrant, which gives his business official status as a supplier of gifts to Queen Elizabeth's household, for the best part of 20 years.

Durkin's royal connections run a little deeper. He fondly remembers the soon-to-be-wedded prince, along with his elder brother Prince William, regularly visiting his bakery after school with their friends when they were teenagers attending the nearby Eton College.

Home to both the queen's residence and Eton, famed for educating royalty and politicians including several prime ministers, Windsor's diminutive size may prove to be a headache for anyone trying to find accommodation for the big day.

"All of the hotels are full, so I'm envisaging the town is nearing full capacity," Durkin said.

Fully booked

When she arrived in London from Brazil in 2009, Jaciara Pereira never envisaged that she would capitalize on such a surge of interest in hotels. Her property rental business consists of 17 properties in Windsor and London. All are fully booked out the weekend of the royal wedding.

Tourists from countries including the U.S., India, Bangladesh and Argentina have spared no expense booking rooms in Notting Hill and Kensington, London's more expensive locations, so that they are able to commute into Windsor by train and soak up the atmosphere.