The appearance of Jacob Zuma in London this week is a carefully-crafted reassurance, for the benefit of the West, that all will be well in South Africa under his leadership. It is also intended to be a demonstration of clear blue water between him and Thabo Mbeki over Zimbabwe. Zuma’s dissatisfaction with Mbeki’s mediatory efforts, and his even greater dissatisfaction with Robert Mugabe, are well-known.

Even so, he chose his words carefully, both praising such mediation that has occurred, and not condemning Mugabe in public. He might, after all, inherit the same troublesome president of Zimbabwe as his neighbour.

But Zuma adds his weight to a growing Southern African regional concern over the contortions in Zimbabwe. Zambia’s President Mwanawasa was forthright in calling upon all neighbouring states not to allow the Chinese ship, carrying arms for Zimbabwe, to dock. The new half-white President Khama of Botswana is unhappy with Mugabe’s rhetoric against residual white ownership of the continent, and many are upset that the Mauritius Protocols on how to conduct free and transparent elections has had the transparency element so visibly flouted in the tortoise pace of counting the votes.

Zuma also has an electoral problem on his own hands. With 3 million Zimbabweans on South African soil, there is a real social and economic problem which will manifest itself in next year’s South African elections. The ANC is frightened that, after the years of lacklustre Mbeki leadership, it will have a greatly reduced majority. Mbeki’s failure to achieve breakthrough in Zimbabwe cannot have helped.

The South African efforts over Zimbabwe have in fact been assiduous. But even the key South African mediators – of the very highest rank and skill – have been frustrated both by Mugabe himself and by Mbeki’s failure to ‘put in the boot’ at critical junctures. There has been a string of instances over two years where agreement had been reached on key issues concerning the Zimbabwean elections, only for Mugabe himself to refuse to honour what his own negotiators had agreed.

There are five reasons for Mbeki’s extraordinary patience. The first is that he does not see Mugabe as a lone figure, but one who owes his increasingly precarious position to the support of his hardline generals. Some say that these generals have already instigated a coup of sorts and Mugabe is their captive. This overstates the issue, but Mbeki knows the hardliners will not disappear at his say-so.

The second is that neither he, nor almost any leader in Africa, sees Morgan Tsvangirai as a viable alternative president. This is unfair to Tsvangirai, who has come a long way and who would accept a unity government to ensure continuity and the preservation of vested interests, but he is a very rough diamond indeed, and the choice is between him and a diamond that cuts the wrong way.

The third is that Mbeki and Mugabe simply get on intellectually. The huge change in tone in the regular ANC newsletters, now that Zuma is writing them, is striking. Gone are the erudite and literary qualities that Mbeki brought. Quite simply, Mbeki and Mugabe are the two intellectuals of the region’s presidents, and Mbeki always thought, wrongly, he could make reason prevail.

The fourth is that Mugabe genuinely holds Mbeki, and many other African presidents, in thrall. His personal charisma and position as the grand old man of liberation gives him both seniority and pedigree that no one else can match. What is taken as senseless rhetoric in the West is a rhetoric of great meaning in a continent where the welts and scars of racism and colonialism will take another generation to heal.

Fifthly, Mbeki simply has blind spots – a capacity for sustained stubbornness even where his preconceptions have been demonstrated as palpably wrong. The HIV/AIDS question was the most famous of these, but dithering over Mugabe’s Zimbabwe will run it close.

The electoral rhetoric of Jacob Zuma will address all of the Mbeki weaknesses. In a very real sense, without a coordinated opposition to face, Zuma must recapture the ANC vote by distancing himself from Mbeki as much as possible. Unfortunately, this will also involve distancing himself from many of Mbeki’s most skilful advisers, and Zuma will replace them with his own hard men and women, not all with savoury backgrounds, who organised his victory as leader of the ANC.

Making a clear distinction between himself and Mbeki over Zimbabwe is in some respects an easy way to start. Zuma is street-smart without being intellectual. He knows that this will win him votes. He knows also the one glaring fact that Mbeki has shrugged aside. With meltdown in Zimbabwe, South Africa’s dream of an integrated economic region has also gone. Five key states with growing economies and stable government would have led the way – South Africa, Zimbabwe, Botswana, Namibia and Zambia. They would have punched their weight economically against the rest of Europe minus the big four of Germany, France, UK and Italy. They would have made an impact, finally, for Africa. Zimbabwe under Robert Mugabe ruined all that.

With his promises to bring a better life to the millions of South Africans who have not benefited from the changes begun by Mbeki, the last thing Zuma needs are desperate Zimbabweans on his doorstep and in his home. There is not that much moral commitment to democracy here, nor to the redress of a humanitarian disaster in a neighbouring country. Mbeki, meanwhile, has made far too much moral commitment to a bankrupt cause and his failure over Robert Mugabe will haunt his reputation for many long years to come.