It took a decade-long campaign and £5.5 million to transform a B-listed building from an eyesore into a thriving community hub on a small island in the Firth of Clyde.

The Isle of Cumbrae’s historic centre, Garrison House, is now the site of a museum, library, cafe and, crucially, the island’s only GP surgery, with a 24-hour, seven-days-a-week medical practice and dispensary service.

But only a year after the former barracks re-opened, residents fear for its future, as it has emerged permission for a new pharmacy has been lodged with the local health board.

The move is likely to lead to Cumbrae Medical Practice losing its right to dispense medication. Staff say this will result in a loss of 55% of the practice’s income, which may jeopardise the jobs of four staff and one doctor, and leave several rooms empty.

Dr Jim Bryson, who has worked at the practice since 1984 with his wife Elizabeth, also a doctor, said: “The main problem is that patient care will suffer. There will be a reduction in services.

“We have been on the island for 26 years, providing a Rolls-Royce type of service, not because we regard ourselves as better doctors but because we’ve got a large subsidy for our dispensary and we are able to employ more staff to provide that service. We would be looking at making five staff redundant, including one doctor, because of the loss of income.

“There is very little in the way of employment on the island, so it’s not as though these people can go and find another job.

“It would seriously compromise the viability of the Garrison building. The people of Millport campaigned for more than 10 years to achieve the restoration of the Garrison and they will be furious to hear that their efforts over the years could be compromised.”

Residents on Cumbrae fear that losing their dispensary in Millport could impact on health services for the island’s 1310 population, many of whom are elderly, with a higher than average number suffering from diabetes and high blood pressure.

Islander Angela Giorgetti, 51, who owns the Ritz Cafe, said: “The local doctors are terrific. They are there for you in the middle of the night. They come back to the pharmacy to pick up your prescription and deliver it to you in the middle of the night. With a population of elderly people that is very important.

June Allison, 65, secretary of the Isle of Cumbrae Elderly Forum, said: “The doctors have given us 25 years of dedicated service. There has never been a minute when this island was without a doctor.

“This is going to make life very difficult for our elderly people. Feelings on the island are running high.”

The applicant, Sarah McSorley, says the pharmacy would be an “augmentation of the current service provided by the dispensing doctors and not competition to (it)”.

But Dr Bryson said there was a question mark over a new pharmacy’s viability, as there was no evidence locals would use one in Millport, rather than a supermarket pharmacy in Largs, on almost daily mainland trips.

A spokesman for the local health board, NHS Ayrshire and Arran, said the proposal was out for consultation until April 16 and responses would be passed to the Pharmaceutical Practices Committee to decide on the application.