Like countless thousands, I spent a good deal of Christmas watching my Live Aid DVD box set. Much of it - Sade, Simple Minds, Nik Kershaw, Kenny "Footloose" Loggins - sent me straight to the fast-forward button. The odd moment had me gawping at the screen, thinking that the 1980s had amounted to a period of collective psychosis: who, I am still wondering, ever came to the conclusion that Spandau Ballet were a good idea? One bit in particular, however, gave off the distinct whiff of genius.

I am talking, of course, about the early-evening set delivered by Queen. It has long been a cliche - but only because it's incontestably true - that they were the only band who fully grasped the event's "global jukebox" concept and gave the TV audience exactly what it required. To collapse one's Greatest Hits album into a quickfire 20 minutes was an inspired move; to deliver the resultant music without putting a foot wrong took them into the orbit of the greats. And Freddie Mercury! Those who compile lists of Great Rock Frontmen and award the top spots to Mick Jagger, Robert Plant et al are guilty of a terrible oversight. Freddie, as evidenced by his Dionysian Live Aid performance, was easily the most godlike of them all.

Back in 1985, however, I can recall turning the TV off in disgust. There were Freddie, Brian, Roger and The Other One shaking their stuff in front of that map-meets-guitar logo and serving notice of their concern for the plight of the third world - but less than 12 months before, as was known to right-on NME readers like me and my friends, they had committed the earth-shaking sin of breaking the United Nations cultural boycott and playing gigs in apartheid South Africa. These days, you don't hear much about this tawdry episode of their progress, so by way of a reminder ...

Queen played a run of shows at Sun City, the entertainment complex located in Bophutswana, one of 10 South African Bantustans: tracts of low-quality land supposedly enshrined as independent black homelands that were in fact one of the struts of the apartheid regime. They amounted to parched rural ghettoes; the fact that the Sun City complex - a casino-and-golf resort, akin to an Afrikaner's Las Vegas - was located in one of them only underlined their cynically conceived place in the apartheid scheme.

"We've thought a lot about the morals of it a lot," claimed Brian May at the time, long alleged to be one of the cleverest men in rock, "and it is something we've decided to do. The band is not political - we play to anybody who wants to come and listen." "Throughout our career we've been a very non-political group," said bassist John Deacon (aka The Other One). "We enjoy going to new places. We've toured America and Europe so many times that it's nice to go somewhere different ... I know there can be a bit of fuss, but apparently we're very popular down there ... Basically, we want to play wherever fans want to see us."

The cloth-headed, deluded, impossibly arrogant nature of these pronouncements hardly needed mentioning. Queen were swiftly fined by the British Musicians' Union, and briefly turned into music press pariahs. They were not alone: the likes of Rod Stewart and Status Quo also played Sun City, easing their consciences by making donations to local charities. Queen were no exception: they attempted to make up for the breaking of the cultural boycott by handing some spare royalties to a school for the deaf and blind. It didn't wash: the UN stuck them on its list of blacklisted artists, where they remained until apartheid was finally dismantled.

In these washed-out, relativist, non-ideological times, bearing a grudge based on all this might look rather churlish, but what the hell: in the wake of their Sun City season, I have always found Queen's alliance with rock's liberal bleeding hearts a little too much to take. Towards the end of Live Aid, for example, Mercury and May played a recently written song called Is This the World We Created?, which took issue with disease, suffering and human evil in general. I waited in vain for a specific reference to the heart-stopping wrongs they had witnessed in Bophutswana, but none came. And what about the utopian sentiments of One Vision, released a year after their South African trip? "No wrong, no right," sang Freddie. "I want to tell you, there's no black and no white." Well, phooey, frankly.

All this came into sharper focus just recently when I read that Brian May, Roger Taylor and the sometime Free vocalist Paul Rodgers are to travel to South Africa in March to play a Nelson Mandela tribute concert. Performing as Queen, they will headline a show aimed at raising money to tackle Aids in sub-Saharan Africa. As with a previous show staged in 2003, it'll go under the banner of a 46664 concert: the number is taken from Mandela's prisoner ID at Robben Island jail.

They will doubtless play Bohemian Rhapsody, Radio GaGa, Hammer to Fall and all the rest of the hits. After that bit's done with, they might also find it in them to finally say sorry.