I FOUND the badge. Faintly embarrassing, but not by much. Dug out the CD, too, of the Special AKA, and allowed myself a whole 30 seconds to recall old Stockbridge, and the select (grubby) parts of certain Newcastle "ballrooms". Interesting times, if you happened to live through one.

Two Tone; and Rock Steady; and a Dubbed Down world. We thought we had cracked it, then, in black and white. But retrospection is a strange, easily-forgotten game, like becoming middle-aged when your back is turned, like hearing your own father's voice in your ears. And nothing is more dreary for anyone who happens, this week, not to be actually old.

Still: Rock Against Racism. No Platform for Racists. Kick Out the BNP. And Free Nelson Mandela That last was a serious matter. To get the comrade out of those filthy racist stink-hole prison pits was, for some of us, everything. It was only exceeded, in fact, by the need to liberate Zimbabwe. How hilarious is that, this morning?

The universe is fond of found irony, one finds. The gulf between the liberated world of which Bob Marley sang and the current Zimbabwean truth is hideous. So we should wait, surely, for a word from Comrade Mandela?

The badge is cheap and mostly green. Mandela's face reflects the last recorded image from the 1960s. He is yellowish in that snap, but smiling. Nevertheless, 20-plus years ago we stood to say that the freeing of Mandela was a moral imperative. For the planet, no less.

Thatcher said he was a terrorist. Even now, in 2008, he is forbidden legal entry to the United States (the War on Nonagerians is endless). So he will have something purely helpful to say, surely, for the raped people of Zimbabwe?

Here we encounter mystery. People I would otherwise trust tell me that South Africa's president, Thabo Mbeki, despises Robert Mugabe. Some whom I also respect attest that Mandela has very little time for his ANC successor, Mr Mbeki, or for that vainglorious thug, Comrade Mugabe - who just stole another election in Zimbabwe. The nations of southern Africa - Lesotho, Zambia, Kenya - are attempting to raise this burden aloft. But where is Mandela?

He is a very old man. This much I know, and I wish him every success after his latest celeb-party in London. I hope, too, that fortunes were raised this weekend for the fight against HIV and Aids he has chosen to wage. I also hope that the old freedom fighter is honoured by all the usual hypocrite hacks. But spare me: Zimbabwe is just a "failure" of leadership? Mugabe is merely "tragic"? Mandela said only that? And this was the best we get?

Not good enough, not even nearly close. I don't care about the vintage of the saint. The geo-politics of southern Africa, the delicate balancing of Mbeki's ambitions, ANC internal politics, and Zanu-PF's pillage should not count in this balance. If Mandela cannot damn these scum finally, and destroy them with a word, Africa has certain moral choices with which it must deal. The possibility of local failure might be one.

Mugabe has exploited the machinations of the white world repeatedly. Quite right, too, I think. Were I the citizen of a young black nation, I would not trust HM's Foreign Office, the UN, the World Bank, the EU, the IMF, the - well, just name it - as utile in my latest local devastating catastrophe.

These white folk come to steal whatever you own. In this, history is consistent. Britain's pasty, pious Anglicans robbed Rhodesia and Zimbabwe blind for decades. But they had nothing, nothing whatever, on Chairman Bob and friends. And the Spear of the Nation must therefore be raised.

HENCE the tragedy of Mandela, and of his failure of will, and of his morality. There is nothing more sickening than the spectacle of some white bloke (like this one) telling Africa what it should, and must, be. Except this: Comrade Bob, it's over. Get on the bus. It, and you, are done. Get out or I, Nelson Mandela, will board a flight to Harare and say the truth to your face. Tomorrow.

How many TV crews would turn out for that? How many Africans would tune in? Who would not want to have that broadcast back, in their faces, to Beijing, the fascist state where Mugabe's future is daily decided?

This is not what the old saint proposes, however. He manages only to squeeze out a word or three concerning failure and leadership. I think we 1970s teens did a little better, slapping pasty Boers and demanding the release of Comrade Mandela.

Melodrama? No doubt. But what was the point, though, of the badge, and the song, and the sentiment, all those years ago? The suffering of Mandela, and the suffering of Africa, conferred a moral authority on mundane struggle. Things were romanticised - of course they were. In the process we acquired a single right: to be sure. But if our only Nelson cannot raise a weapon for African people, who were we, and who was he?

Unfair? Of course. The old man has done things of which I would not dare to dream. First and above all, he has raised all Africa above the patronising gibberish that passes for white discourse. He is not owned: that's liberation. But that is also the overwhelming irony - Africa must deal with Mugabe, the liberator born of a national struggle, and there is only one African who could call him to account.

You get stuck, sometimes, on the barbed wire of dire truth. What if Mandela was a little less than eloquent, a little less than perfect, or some degree short of saintly? What if he is failing to demand a resolution to Mugabe's horrors just because he can see no African answer, or supply the same? Does the white man then pick up his burden? Do we then talk nonsense about "intervention"?

Mandela should advocate a South African invasion of Zimbabwe. The world would heave a sigh of relief. Neither - least of all the sigh - is going to happen. But here's a thing about freeing Mandela, all those years ago: the world was supposed to change. What's more, the prisoner himself believed it. This is not, these days, the old man's view.

I count that a pity. I count it pitiable, too, that we are so purblind as to believe that the argument still depends on the idea of "intervention". Some things have a point, some do not. Iraq: stupid. Bosnia: arguable. Zimbabwe: destroy the bastard.

I offer this, for what it's worth. The longer the world lingers over Mugabe, the more certain a humanitarian catastrophe will become. Check your history books - insanity is loose, and there is no end to that appetite.

Mandela must know as much. Mandela, if he is half the Marxist I believe him to be, knows history from front to back. But he must also know this. Zimbabwe is a crisis for the world, but it is better understood as a crisis for Africa, of Africa.

No more blaming the whites for cutting a deal for the latest platinum mine. No more blaming Washington, or London, or Paris. Blame them for their banks or their hedge funds or their debt-to-aid ratios. Everything you say will be entirely true. That is not, though, the whole tale. Only one person can deal with Mugabe and the desecration of every African ideal in a sick, abused continent. Only one man has - can I say this? - the balls. It is sheer impertinence, I know, to demand such a thing of an exhausted hero.

But just get on the plane to Harare, old man, and throw him out.

It wouldn't pass for democracy, of course. No one would call it "legitimate". My naff, ancient, blistered badge says, nevertheless "Free Nelson Mandela". Time to return the sentiment, I think.