 It proved expensive to maintain and the surrounding land was gradually sold off, until the Southampton University Hospital NHS Trust finally decided to close it in 1998.Fairmist Limited, a firm of property developers, purchased Netley Castle in 2000 and converted it into nine private residential flats, at a cost of £1.7 million, during which process an archaeological survey was made of the property.It is protected under UK law as a Scheduled Monument and a Grade II* listed building.