The support of people like Wilson - best known as the curmudgeonly Victor Meldrew of One Foot in the Grave - and the publicity which they can attract - is vital to the VSO in its 40th birthday year. For today the organisation is to announce that it faces a chronic shortage of the right sort of volunteers.
In some skills areas their numbers have halved in two years. Mr Blair's message about caring Britons seems to be falling on deaf ears, at least amongst people of "prime" working age - the mid-twenties to mid-thirties - who, the Charities Aid Foundation notes, are not volunteering as they used to. VSO in part blames the "Feel Great" society. But it is not just selfishness which is cited by Simon Watts, its spokesman. "We do live in a Me-first society," he says. "But actually VSO has a part in that. It could be self-interest which would bring people to VSO. People do work with 10 times the responsibility they'd get in the UK, working unsupervised for much of the time. We need to get that message across to everyone, including business."
Another problem VSO has to contend with is that younger people simply have not heard of it. Yet VSO is held in much affection by its past alumni, amongst them high-flyers such as James Lowden, group finance director of Blue Circle, which made VSO one of its charities of the year in 1996 and 1997. Jon Snow, of Channel 4 News, cites his VSO experience as a watershed in his life.
The current generation of nearly 2,000 volunteers also needs to be more skilled than their forerunners. They are often in mid-career, and professional. According to Fiona Lewis, VSO's head of placements, "Years ago, say within education, volunteers could go overseas who weren't qualified teachers. Now, as a broad generalisation, we provide skills which cannot be found in-country. So we don't just send foresters but forestry lecturers."
VSO needs people who are at the stage in their lives when they are likely to be at the height of their careers, or already have their own families. That makes the strong characters whom Wilson met volunteering all the more remarkable. Elles Santegoets, in her 40s, was recruited through VSO's Dutch offshoot. She gave up working with prostitutes in Holland to work in Davao. "It's like there's this little empty space that you want to fill up," she said. "It's as though I have found the last missing piece of my life."
Like many VSO workers, Santegoets is in the Philippines at the invitation of VSO's NG0 (non-governmental organisation) partner, which pays half her salary. The workers' stays are hardly ever longer than two years. They need to build something which will outlive their secondment.
Working among stunning rice terraces in the mountainous north of the country, Simon Taylor and a local colleague from the Philippines' Rural Reconstruction Movement were introducing micro-machines which use streams to generate electricity or to grind rice. But it was important that Taylor transferred the right habits and enthusiasm to others. Otherwise the machines he left behind would break and rust through neglect.
The important achievement for VSO people is that they not only help to produce a basket, or a mill or a fish, or help a prostitute avoid disease. It's not even merely someone better educated. It's a strengthened local, often volunteer, institution which really counts.
Local NGOs are the cement of the emerging informal democracy in the poor world, and VSO is helping its partners prove that surprisingly often, you don't have to be rich and powerful to influence events.
Victor Meldrew would probably approve: his is a battle against the getting and spending, and the littering, Yahoos he sees about him. Under his carapace, there might even be that increasingly elusive figure, a VSO field worker.
If you are interested in VSO's work, you can visit a special fair, Volunteering World, this Saturday atWestminster Central Hall, London, free. Enquiries 0181-780 7500, manned on Saturday.