The closer one scrutinises the assumption that Jacob Zuma has a presumptive right to succeed Thabo Mbeki as ANC president by virtue of his position as deputy president, the less convincing it becomes, however much the ANC Youth League would have the nation believe differently.

The ANC website highlights the importance of two positions: the offices of president and the secretary-general. It lists all 12 presidents and all 13 secretary-generals since the ANC's formation in 1912. There is no corresponding list of ANC deputy presidents on the website.

A conclusion that might be drawn from the information on the website is that the position of the secretary-general is at least as likely to confer presumptive rights as that of deputy president.

From that deduction another follows. The present ANC secretary-general, Kgalema Motlanthe, has as strong a claim to succeed Mbeki as ANC president as Zuma.

The deduction may have more than theoretical interest in light of an increasing tendency in the media to identify Motlanthe as a contestant in the anticipated succession struggle and perhaps the one that has the best chance of defeating Zuma in view of his reported backing by no less a person than Mbeki himself.

A look at the career of Oliver Tambo, who served as acting ANC president from 1967 to 1977 and then as ANC president from 1977 to 1991, offers no clear-cut answers as to whether occupancy of the office of secretary-general or that of deputy president confers the stronger right to the presidency of the ANC.

Thomas Karis, Gwendolen Carter and Gail Gerhart record in volume 4 of their massive documentary history of African politics in South Africa that Tambo was elected to fill the new position of deputy president in 1958 because the then ANC president, Albert Luthuli was restricted to his home in Natal by the minority white government.

But a qualifying rider must be added: Tambo at that time was the ANC's secretary-general, from which the inference can be drawn that he was promoted to the role of a caretaker deputy president because of his occupancy of the office of secretary-general.

A related deduction follows: the new office of deputy president was especially established in anticipation that the outlawing of the ANC was imminent and that contingency arrangements were necessary.

For clarification yet another point needs to made: the ANC was already planning to send Tambo abroad to serve as its spokesperson and wanted him to have a status commensurate with his new position as head of the ANC mission in exile.

From the above it can be concluded that the office of deputy president was created to meet the exigencies posed by a grave situation, not to confer an heir-apparent status on the occupant.

It must be added, though, that the deputy president was obviously not excluded from promotion to the presidency and that Tambo did, indeed, become successively acting president when Lutuli died in 1967 and president 10 years later.

Cognisance should be taken of four events after Tambo became the ANC president, all of which provide an interesting perspective on the position of deputy president.

When Tambo became president of the ANC in 1977, no one was appointed to serve as deputy president, which suggests that the position was neither viewed as dispensable to the smooth functioning of the ANC nor as a vital training ground for the exercise of full presidential power.

The position of deputy president was, however, revived in 1990 and conferred on Nelson Mandela. It was necessary to do so in order to accommodate Mandela in the uppermost echelons of the ANC.

The move, however, was made even more imperative as Tambo had suffered a severe stroke in 1989 and was unable to bear the heavy responsibilities of his high office.

Mandela was elected president at the ANC's national conference in Durban in 1991, not because he had served as deputy president but, rather, in recognition of his contribution to the struggle and his importance to the ANC in the settlement negotiations and in South Africa's pending first election based on universal adult suffrage.

Mandela's fellow Robben Island prisoner, Walter Sisulu, was elected as deputy president at the same national conference.

Sisulu, however, did not go on to become president in succession in Mandela.

Instead he continued to serve the ANC in a more humble capacity until his death in 2003.

Viewed through the prism of history, it is a gross simplification to present the position of deputy president as one that leads ineluctably to that of president.

Not all ANC presidents served an apprenticeship as deputy president, including men of the calibre of Lutuli and A B Xuma.

By the same token not all deputy presidents became presidents, as the career of Sisulu illustrates and that of Zuma may yet confirm.

The office of deputy president seems to have filled different purposes at different times, including the forging of contingency plans to address particular crises.

As Tom Lodge, professor of political studies at the University of the Witwatersrand observes, in asserting its belief that Zuma has a peremptory right to become ANC president, the ANC Youth League appears to be seeking to enhance its image as a king-maker rather than offering an accurate account of ANC tradition.

To argue against the notion that the weight of historical tradition makes Zuma's accession to the presidential office a certainty is not, however, to deny that he may become president.

But that will depend largely on his ability to survive the fallout from the trial for corruption and fraud of his financial advisor, Schabir Shaik.

Zuma is on record as denying that he met Alain Thetard, of the French-based armaments company on March 11 2000 (where he allegedly touted for a protection fee of R500 000 a year).

Shaik, however, has told the Durban High Court that a meeting between the three men did take place at Zuma's official residence on March 10 2000.

Zuma's parliamentary statement raises the suspicion that he was disingenuously deceiving parliament by not admitting that the meeting had taken place the day before.

By not doing so, he has reinforced misgivings about his financial probity and, in the process, imperilled his chances of becoming president.

The Star's Contributing Editor Patrick Laurence is the editor of Focus, journal of the Helen Suzman Foundation.

With acknowledgements to Patrick Laurence and The Star.