Each time I've returned to South Africa in the past decade or so the pace of political change has been breathtaking.

After all, 10 years ago Nelson Mandela was still in prison, and a black majority government seemed a distant prospect.

Even five years ago the old white National Party was a powerful player, and the diehards to the right of them - Eugene Terreblanche and his crew - were threatening all manner of disruption and disaster.

It's hard to appreciate, if you've not been a regular visitor, just how fundamental the shifts have been.

Political change

Nelson Mandela was in prison 10 years ago

Driving through Johannesburg's rich Northern suburbs - carefully, though, with car windows closed and every door locked, especially at red traffic lights - the election posters on every lamp post tell a tale.

Above Thabo Mbeki's picture on the ANC's stickers is an injunction in Afrikaans. It's the language of the old oppressor of course - the ANC wants to be all-embracing, even if that means chasing a former enemy's vote.

Down in the Cape, where the National Party is now the New National Party, Gerald Morkel, a Cape Coloured, is on the posters inviting white votes to see off the very real ANC threat to his power base.

The mostly white Democratic party - once Helen Suzman's domain - has a belligerent message about "Fighting Back" in African languages - Zulu or Xhosa. It's all really quite confusing.

Until you take a drive down into the Orange Free State.

Here, some of the certainties of the old South Africa seem welded into place.

The rich wheat and maize farmlands stretch out under a vast sky. Every now and then sand dumps and winding gear tell you that it's gold mining territory too. The farmers and their wives in new Mercedes cars roar past on their way to the Agricultural Show.

In Potchefstroom - we're in Boer War battle territory - a sign, in Afrikaans, points the way to the local concentration camp. It was here, locals will tell you, that the British invented the camps, and fed ground glass to the Boer women and children.

Bothaville, down the road, is much smaller. It has several churches, a black township separated from the white homes, and a railway station.

The local white policeman, guns on his hip, stands on the railway platform, leaning against the wall. Behind him a metal sign has had its message rubbed out - could it have said "Net Blankes - Whites Only"?

Just along the station platform a black school choir is singing the ANC's song which is now South Africa's: "Nkosi iSikele - God Bless Africa". Then they swoop into the old white anthem "Die Stem - the Call", with its references to ox wagons and living and dying for your country.

I watch the policeman's face carefully. Not a flicker. Perhaps the irony has passed him by. After all, Bothaville's had a black mayor for five years now, and a few yards away he's making a formal speech of greeting to the people on board a newly-arrived train.

The train to Bothaville

Fear on the streets in the suburbs of Johannesburg

It's the Phelophepa Health Train, a mobile clinic which criss-crosses South Africa for nine months of the year, bringing basic health care - eye tests, blood tests and hygiene advice - to some of the most deprived areas in the land.

The staff on the train, and their Bothaville patients, tell their own story of the new South Africa, and of some enduring problems.

Lilian Cingo, the black train manager, and her white optometrist and his Coloured staff, describe what they're dealing with - beneath the First World surface of an apparently prosperous country, here is Third World deprivation and disease.

More than half of South Africans live below the poverty line. Most of them are in the rural areas, and the vast majority, like these people waiting patiently to be seen, are black.

Today there are also among them several white people: a man in a wheelchair, a woman in threadbare slacks - probably they've never been attended by a black doctor before. And here, in a tiny town - a "dorp" as they call it in South Africa - there's suddenly reason to hope.

The train has already treated over 12,000 people in this way, so far this year. So here's an example of good sense and good will, multicultural and multiracial, achieving something positive.