Tynedale Horticultural Service has been based at Haydon Bridge High School’s Ridley Hall boarding wing since 1994.

The group, run by Northumberland County Council, has 15 service users, who have maintained the Georgian house’s extensive grounds for over two decades.

But uncertainty over the availability of Ridley Hall in recent months has sparked fears over the future of the horticultural service.

Boarders moved out of the hall in March and in May the school confirmed that boarding provision would no longer be continued.

Last week, the Evans family, which owns the property, said it could be sold to an unidentified prospective buyer before the end of September.

On Wednesday, the county council confirmed that Tynedale Horticultural Service was on the verge of moving to a new home at the Minsteracres Retreat Centre, near Slaley.

A spokesman for the council said: “We have agreed with the Minsteracres Retreat Centre near Slaley that we will transfer our learning disability day service to their estate when we leave Ridley Hall on September 22.

“Initially this will be under a temporary arrangement, but we are in discussion with the centre about it subsequently becoming the long-term base for the service.”

Over the past decade, Ridley Hall has also been home to the Interact Club, a junior offshoot of Rotary International.

Its members – all of which were school boarders based at Ridley Hall – raised thousands of pounds for charitable causes.