After nearly 70 years of producing royal merchandise, British luxury gift manufacturer Halcyon Days is hoping the upcoming wedding of Prince Harry and his U.S. fiancee Meghan Markle will be a happy one for them as well as the bride and groom.

May's wedding at Queen Elizabeth's Windsor Castle home could boost the UK economy by as much as one billion pounds according to one estimate, and Halcyon Days said it would expect its sales to rise by 10 to 15 percent.

"There's a huge opportunity for us to merchandise product around events like this," said Pamela Harper, Halcyon Days' chief executive.

"You know I think it's there for all to see how important, joyous, national events like this can bring very good things to the life of the nation whether that's in the tourism industry, or for hotels and restaurants, hospitality, or for small businesses like ours."

Since the engagement was announced last November, there has been huge media attention on the couple, with Harry, the fifth-in-line to the throne, one of the most popular members of the British royal family and Markle an actress known for her role in U.S. TV drama "Suits".

"We believe that the overall value to the UK economy is going to be just over a billion pounds," said Richard Haigh, managing director of consultancy Brand Finance.

"We originally estimated it would be about 500 million back in January but considering the excitement in the last couple of months, we've revised that up," he added.

At the Halcyon Days ceramics factory in Stoke-on-Trent, a city in central England famed for its pottery, porcelains and bone china, the firm is busy manufacturing a range of mugs, plates and teapots to commemorate the marriage.

The firm is one of only 14 to hold royal warrants - a certificate for providing goods and services to the royal households - from the queen, her husband Prince Philip and heir-to-the-throne Prince Charles.

"It's part and parcel of who we are," said Harper. "There's been a huge amount of interest in the wedding. It's absolutely really positive for the economy as a whole, definitely."