Residents fear the probation office building in Rosslyn Crescent could swiftly become a derelict eyesore after it was confirmed the facility had closed for good.
Harrow Council, which is the freeholder of the building, has said it is looking for a new tenant.
However, the erection of an imposing chain-link fence around the site suggests it could remain empty for some time.
If a new occupant cannot be found then the land may well be sold off to make way for more news homes as Harrow strives to hit housing targets.
“The probation office is an incredibly ugly breeze block building and now a big metal fence has been erected making it look even worse,” said Rosslyn resident Jo Stephenson.
“I’m worried it could be left like that for months which won’t be good for the area. I don’t think anyone will be sad if the building is knocked down but residents will obviously want to know more about any plans to replace it with flats or business premises.”
Greenhill councillor Keith Ferry confirmed the freehold of the former probation centre was held by Harrow Council and that the probation service’s lease had expired.
“The council has secured the property whilst we search for a new tenant,” he told HCRA.
If a new tenant is not found then the most likely course of action will be to redevelop the site amid pressure to build thousands of new homes in the borough, which has led to a flurry of applications.
Plans to demolish outdated office buildings on the opposite arm of Rosslyn Crescent and build more than 50 new homes have been submitted to Harrow Council.
A large-scale HMO (house of multiple occupation) was recently built at the top of Woodlands Road and there are plans to redevelop Watkins House care home at other end of the street.
Meanwhile local people are steeling themselves for the major redevelopment of the Civic Centre site with plans for 850 new homes.