Britain's high street is suffering from weak consumer spending and intense competition, with the likes of burger chain Byron and Italian food restaurant Prezzo closing stores this year.

App-based food delivery services such as Deliveroo and Just Eat are challenging traditional players, and Barclays said that restaurants could even use such platforms to boost their revenues with round-the-clock takeaways.

"The current leisure environment does present a number of challenges for the sector's businesses," said Mike Saul, Head of Hospitality and Leisure at Barclays.

"Those that don't adapt to this type of newly developing consumer demand risk being left behind in this ever-competitive environment."

Restaurants, takeaway meal outlets and pubs, bars and clubs could make an extra 5.5 billion pounds in revenue each year by adjusting their opening hours, the research by Barclays said.

Including gyms, cinemas and other leisure operators, the total annual benefit for the industry could be 6.75 billion pounds in total.

The study, which surveyed 2,334 people and 553 businesses, found that a fifth of British workers expected 24-hour services across the hospitality and leisure sector.

It also found that while 42 percent of businesses had received requests for more flexible opening hours, only 4 percent said that they perceived a loss of business through not being open when customers want.

"While a significant number of consumers experience frustrated demand, most UK leisure services believe they are keeping up with their customers' opening requirements," the report said.

"With many customers prepared to pay a small premium for services at unusual hours, businesses that find ways to meet this pent-up demand stand to grasp a significant opportunity."

(Reporting by Alistair Smout; editing by Stephen Addison)