Roughly a mile square and home to up to 500,000 people, Alexandra could be mistaken for the kind of fetid, violent slum that the Old Labour Party grew out of, all those long years ago, if you took away the African sunshine, that is. And as the Prime Minister's heavily guarded motorcade swept past the squatter shanties along the garbage-filled Jukskei river, a lowering Highveld thunderstorm was doing just that.
At the Alexandra Clinic the mood was much brighter. The Prime Minister and his wife, Cherie, were there to announce pounds 1.9m in UK funding for a mass- media programme to combat South Africa's appallingly high incidence of violence against women. A host of local dignitaries dodged in among the camera tripods to show their appreciation.
A colourful choir sang Zulu Te Deums to Britain's first couple, while Cherie bopped her chin in time and Tony stooped in the dust to pat an African child on the head.
Outside the hall a bulletin board proclaimed "the user- friendly theme of the week", which read: "Try to be happy in your workplace", and "Practise random acts of kindness and senseless beauty".
Home-grown slogans, it turned out, and not the work of Third Way spin- doctors, but then Mr Blair visited this same clinic while in opposition two years ago and perhaps some of his magic rubbed off.
But any cynicism lurking at the back of the clinic's tin-roofed hall quickly evaporated when Mmabatho Ramagoshi, chairwoman of the National Network on Violence Against Women, described the prevalence of rape in South Africa.
Another non-government organisation, Community Information, Empowerment and Transparency, found that, of 1,500 young people between 14 and 18- years-old surveyed recently, one third had suffered sexual abuse and 12 per cent of the boys said they had had sex without the consent of the girl.
A worker at the centre said: "Violence against women in this country has reached epidemic proportions. South Africa is regarded as the rape capital of the world."
Then the Soul City non-profit media organisation aired a clip from its forthcoming, partly UK-funded, public-education television soap opera.
The Blairs watched as the soap's upwardly mobile black middle-class school teacher, played by the cherubic Patrick Shai ("Christmas" in the BBC's biopic of Cecil Rhodes) turned into a chillingly convincing wife batterer at the drop of a gender-role-challenge.
The mainly black audience broke into knowing laughter as Mr Shai later told his son: "I hope that one day you'll understand that when you are in your own home you have to be a captain, otherwise the ship will sink."
Afterwards an obviously emotional Mr Blair rose to say that Britain was supporting the public-education project because it was a vital step towards building a strong and decent South Africa from the brutalised legacy of apartheid.
"The reason why we feel violence against women is such an important issue is not only that the statistics in South Africa are so frightening but because it has an impact of degrading and dehumanising life in civil society, " he said.
Then it was across Louis Botha Avenue to Johannesburg's white northern suburbs, for a reception with the business community.