When it first opened treatment was received by payment only: admissions were only taken at 11 o'clock every morning (except Sundays) and if you hadn't paid your one guinea a year subscription to the hospital (a kind of insurance to ensure treatment when it was needed) you were charged sixpence on admission and were then required to pay a further guinea for further treatment. If you were too poor to pay these fees, you went to the workhouse.
In the late Victorian period, Florence Nightingale (whose family lived nearby) did a lot of fundraising for the hospital, keeping the admission fees low, ensuring the hospital was able to treat more people.
It was the main hospital for the town of Aylesbury all the way through to 1948 when Stoke Mandeville Hospital on the outskirts of town was expanded and took over that role. From that time it became a maternity hospital until the 1990s when a new maternity wing was opened at Stoke Mandeville.
The Royal Bucks, as it had become known, stood empty for a few years, before being renovated and turned into a private hospital for the treatment of spinal injuries. It is for this purpose that the hospital is used today.