Thousands of older people are "trapped" in their homes because of a lack of suitable transport, a new report has claimed.
The WRVS said as many as a third of a million over-75s are being unnecessarily socially excluded.
Cuts in public transport services have made the position worse and are having a "devastating" impact on older people's sense of happiness, said the charity.
A survey of 900 people in Britain over the age of 75 found that almost a fifth do not use public transport because it is not suitable for their disabilities, even though they are eligible for free travel.
David McCullough, WRVS chief executive, said: "Older people shouldn't be confined to their own homes simply because they can't access to transport.
"Getting out and about is a basic necessity that many of us take for granted but this report shows it isn't so straightforward for older people, who may have mobility issues, and we know this can have a devastating impact on wellbeing.
"Helping older people to stay active is vital for their good health and ensuring they remain connected is a really important factor in an inclusive society."
Bob Crow, general secretary of the Rail, Maritime and Transport union, said: "The shocking news that around a third of a million older people are being socially excluded through transport poverty should have this government hanging their heads in shame.
"The cuts to station and train staff being bulldozed through by the private train operators and the Government will worsen this scandalous situation and RMT will work with pensioners' groups to fight for access to transport services for all."
A Department of Transport spokesman said: "We know that transport is absolutely crucial for older people which is why we are investing in facilities for people who are less mobile, like new lifts and ramps at railway and bus stations, and spent £1.77 billion last year on supporting bus travel which is particularly important to older people.
"We have also protected the bus concessionary travel scheme in full and provided a further £10 million for community transport in rural areas. All of these demonstrate that the Government understands the problems faced by older people and is taking decisive and practical measures to help."