Barely two weeks after the death of one of South Africa's great political leaders, Walter Sisulu, 22 rightwingers are facing charges of treason in the very courthouse in which Sisulu and Nelson Mandela were jailed for life in the infamous Rivonia treason trial exactly 40 years ago.

The irony is probably wasted on many, but it is a timely reminder of how the wheel has turned.

Back in 1963, few could have guessed that history would treat Sisulu kindly. Together with past president Nelson Mandela and Oliver Tambo, Sisulu was a driving force behind the African National Congress (ANC), which fought to free South Africans of the yoke of apartheid. He quickly became one of the most arrested men in the country, and the biggest surprise about his trial was that he and Mandela escaped capital punishment.

After spending nearly 30 years on Robben Island as a political prisoner, Sisulu chose to play no formal role in South Africa's post-apartheid government in the 90s, but his low public profile belied his behind-the- scenes involvement in the ANC's ongoing transition from liberation movement to governing party.

His death, a few weeks before his 91st birthday, has raised a deeply disturbing spectre for many South Africans: what will happen when his comrade-in-arms Nelson Mandela, who is in his mid- eighties, dies. Many see Mandela as the glue that has held the country's fractious political and ethnic groupings together, and Sisulu's passing is an uncomfortable reminder that the country cannot rely on iconic personalities to get by forever.

If anybody needed any evidence of just how fractious some of these minorities are, one need look no further than the pending trial of the 22 rightwingers accused of plotting to overthrow the government last year.

What will happen when Nelson Mandela, who is in his mid-eighties, dies?

The group, known as the Boeremag (the Afrikaner Force), is said to have masterminded several bomb attacks on railway lines and a Buddhist temple last October. It also planned to assassinate Mandela himself, which would almost certainly have taken the country to the brink of a racially-based civil war.

The most sobering aspect of the entire plot is the fact that the plotters are not wild-eyed hillbillies high on moonshine. The leadership of the Boeremag included wealthy doctors, businessmen and former military officers.

Intelligent, thinking men, in other words. When they finally get to court, they intend to argue that the previous government of FW de Klerk had no mandate to enter into negotiations with the ANC, and set the process of democracy in motion. The current government is therefore illegitimate, and they are therefore not subject to its jurisdiction.

Of course, that doesn't stop them from accepting legal aid from this illegitimate government. Their disingenuous counter to that is that it is the state which is putting them through the ordeal of the trial, and the state should therefore pay.

The Boeremag has managed to win sympathy, if not support, from disaffected Afrikaners by highlighting issues of popular discontent - genuinely high levels of violent crime, rising white unemployment and the bogeyman of land grabs in neighbouring Zimbabwe.

And if you happen to question how life in an Afrikaner republic would be any different, they will resort to less conventional methods of persuasion. The lone Boeremag member to have entered a plea bargain with the state told the court that his recruiters showed him a video featuring the predictions of Boer prophet 'Siener' (literally, seer) van Rensburg.

In the video, Van Rensburg warns his white brethren to be ready to counter a plan by black South Africans to 'create chaos' in Johannesburg, and talks of 'buckets of blood' being upended in the north.

And their self-righteous lunacy doesn't stop there, either. They have established a group of shadowy underground cells known as 'Die Uile1 (The Owls), named after a boys'gang featured in a series of Afrikaans adventure books.

The main mission of The Owls is to find the informers who tipped off the police about their activities, and they have circulated a list of 70 Verraaiers', or traitors, in right-wing circles.

If their intentions weren't so serious, it would be a hoot. But we can be sure that Walter Sisulu will be watching proceedings in the Palace of Justice with a keen eye.