There are fears for the future of dozens of shops in the borough which will lose business if seven post offices are closed.
New research from the charity Help The Aged shows 950,000 pensioners across the capital will have to travel at least an extra half mile to find a replacement for their local post office if it is closed, and the effect on shops close to it could be catastrophic.
The charity Age Concern Hillingdon has pointed out that with pensioners going else-where, other local businesses would soon suffer as a direct result and old people themselves could be at risk.
Chris Commerford, the charity's chief officer, said: "It is absolutely shocking. The fact that more closures are on the way will have a really negative effect on old people, and also the parade of shops they used to visit, because in my experience the post office is what attracts old people along, so it could lead to other shops closing.
"The post office provides somewhere they can meet their friends, and the postmaster will know that if they haven't come in there may be something wrong.
"It really will make old people more vulnerable."
In May, seven post offices were put forward for closure in the borough, one in each of West Drayton, Northwood, Ruislip, Cowley and Uxbridge, and two in Hayes.
John Randall, Conservative MP for Uxbridge and West Drayton, said: "I did campaign against the closures of the post offices in my constituency because the overriding thing was that elderly and disabled people, or those with mobility problems, would be disadvantaged.
"A network of sub-post offices is essential for elderly people. They are losing a valuable asset to their community. It is where they go to meet and chat; now they will have to go elsewhere or not at all."
A Post Office spokesman said: "The closure of any post office is always difficult, but Post Office Ltd is conscious of the needs of elderly customers and is implementing the plans to close up to 2,500 branches as sensitively as possible.
"About 20 per cent of initial proposals for closure have been changed on the basis of information received during local planning and consultation."
However, it is estimated that nearly 500 hours of meetings have taken place nationwide in a bid to save post offices, but fewer than four per cent of the branches earmarked for closure have been reprieved.
The consumer watchdog Post Watch believes some 2,480 branches will closed by the end of the year.