Mandela declared in the wake of his son's death: "Let us give publicity to HIV/Aids and not hide it, because the only way to make it appear like a normal illness like TB, like cancer, is always to come out and to say somebody has died because of HIV/Aids."
Yet while his taboo-busting statement made headlines around the world, it has been all but ignored by the powers that be in South Africa, where more than 10 per cent of the population have the virus.
Even though it is known that many members of the ruling party, the ANC, have died of Aids, while many more are receiving anti-retroviral drugs to treat their condition, no other politician in South Africa has so far responded in kind to Mandela's plea.
In fact, Smith's declaration probably makes him the most senior politician in the world to have declared himself HIV positive. Such singularity is not new to Smith, since he became the first openly gay MP in Britain, in 1984.
The climate in those days was far more hostile towards homosexuality, with Aids and HIV only beginning to emerge as a major public health issue. The stigma attached to homosexuality at the time was such that when Peter Tatchell had stood as a Labour candidate the year before in Bermondsey, a smear campaign about his "ambiguous" sexuality ruined his mainstream political career.
Indeed, while Tatchell has warmly welcomed Smith's declaration, he has also suggested that Smith might have been braver to have announced his condition earlier. It's easy to say why an activist might believe this. In the late Eighties and early Nineties, fear of Aids was hugely fuelling homophobia, and perhaps a stand from Smith would have made a difference. That point is debatable, but what is less debatable is whether it would have had a great deal of impact on the direction of Smith's political career.
First, he would have been under even greater pressure to become what he did not want to become - a single-issue politician. As a gay politician anyway, Smith had plenty of opportunity to be involved in shaping policy on Aids, and in fact served as vice-chairman of the all-party Aids Parliamentary Group from 1987 until he became culture minister in 1997. Had he been openly HIV all of that work would have taken on a personal emphasis that might have been counterproductive.
Second, he would have found himself associated with an image of male homosexuality that was still widely unacceptable. By the late Eighties Smith was safely ensconced with a long-term partner, Dorian Jabri, in the sort of committed gay relationship that soothed the brows of those who fretted about "gay promiscuity" but were willing to accept a version of gay sexuality that was much less threatening.
"Vanilla sex" was all the rage in the Eighties, with the fight for gay acceptance very much fronted up by the idea that discrimination was thwarting the path of true and lifelong love. It was not until later that a more truthful portrayal of what, in Father Ted, was referred to as "the rough and tumble of homosexual life" became acceptable.
When he was asked by a journalist after announcing his HIV status whether he knew who he had contracted it from, Smith admitted frankly that he has "no idea". In 1987 it would have been much harder for him to have been candid. At that time there was still a widely held belief that the "gay plague" was a punishment for indiscriminate immorality. Smith's acceptance in the mainstream of political life has been a positive detail in the advancement of gay rights. His stable relationship and seeming distance from gay hedonism have certainly not harmed his acceptability.
That is not to say, however, that in a British context there is no risk - and no meaning - in his decision to go public now. It might not be the almost recklessly courageous step it would have been 20 years ago. But even now, as his parliamentary career comes to an end (he is not standing for re-election), there are plenty of people who will try to use this development against him. Yesterday's Daily Mail, for example, carried the absurdly loaded headline: "Brave or just a cynical ploy by a grey man who craves praise?". The implication behind this rhetorically biased question is that nowadays people can expect to be rewarded for being gay, and that Smith is intending to cash in on an illness that can be used to his financial advantage as well as a boost to his ego in terms of attention and admiration.
Such propaganda, however, is just one manifestation of a new sort of prejudice, which attacks people more subtly than before by complaining that somehow their victimhood is being rewarded.
It is seen not just with the idea that one is specially feted because of positive discrimination as a homosexual. It happens with class as well - particularly with the right-wing idea that a third-rate education at a failing comprehensive will propel people into Oxbridge ahead of their own expensively educated geniuses. It happens with race too, with the idea that somehow being born poor in a country that abuses your human rights is a passport to British nationality that a mere Anglo-Saxon born in Much Deeping could not hope to compete with.
And it is dangerous. In these times, with liberal acceptance and celebration co-existing with continuing distrust and anger, anyone who is a little bit different still has to walk a tightrope. The increase in hate attacks on the streets of Britain is unwelcome evidence that with freedom comes risk.
Behind Britain's liberality lurks anger and intractability. This anger is often taken out on homosexual men, who report a huge rise in homophobic attacks. On the international stage, unfortunately and for various reasons, that situation is even more awful.
The Italian politician, Rocco Buttiglione, managed to stir up widespread sympathy when he was rejected as an EU commissioner - his homophobia, he explained, was an intrinsic part of the Catholic faith. Various Jamaican dancehall stars, eager to broadcast lyrics inciting the murder of homosexuals, are likewise defended as being the products of their culture. Ken Livingstone (who ironically enough is throwing a pounds 10,000 public reception to mark the 20th anniversary of Smith's coming-out), has taken to defending Muslim clerics who condemn homosexuality in the strongest terms on similar grounds.
In Britain, legislatively at least, the majority of gay rights battles have been won. But while it might seem in a nation that laps up Queer As Folk and Graham Norton that gay culture, in all its messy and subversive glory, is not just accepted but adored, this impression is not true, or at least not true for everyone. Those who will not accept gay equality, all around the world, are determined not to be ignored. But they must be. Chris Smith may not even recognise that what he has done is still important, in Britain as well as internationally.