Dona Ana Joaquina dos Santos e Silva was the most renowned high society hostess of 19th century Luanda. She was an Angolan of African and Portuguese descent. She made her money by selling other Angolans and shipping them to slavery in the Americas. The person who first told me about Dona Ana Joaquina was Rafael Marques. It must have been 2001. We were driving through Luanda’s Cidade Baixa, the downtown which, at the beginning of this century, was still defined by dank and sometimes half-ruined colonial buildings. Signboards with the names of Portuguese and Brazilian companies staked out the building sites, where the Baixa of today – the Baixa of glassy banks and corporate headquarters – was starting to push upwards through the compost of the old.

One construction site was different. Concrete was still the raw material, but on the façade of this new building the grey stuff was being moulded into the ledges and cornices more typical of the buildings that were crumbling nearby. This was the former home and warehouse of Dona Ana Joaquina. A mix-up somewhere in government – the pursuit of profit coming up against nostalgia for the city’s slaving past – had led to an order to demolish the building, and then to another order to rebuild it. The new-old building was to be put to use as a court of justice. Rafael explained all this with his relish for the absurd that he deploys as a way of dealing with a country in which the absurd is the stuff of everyday life.

It was in this facsimile of a slave house that Rafael has stood trial over the past few months, facing charges of libel brought by Angolan generals turned mining magnates who felt offended by his exposure of human rights abuses in the diamond industry. The few photos that were sneaked out of the court before the session was closed to the public showed light-skinned generals deploying the might of the state against a lone black journalist: a sight that might have surprised those unfamiliar with Angola’s race politics.

Today’s Angolan elite has become richer than ever before on the back of petroleum sales, but it owes its ascendancy to the slave economy of centuries past. Although the Angolan coast was for hundreds of years under the political control of Portugal, colonisation was a relatively hands-off affair, and the rulers of the metropole were content to leave the running of the economy to a class of mixed-race and creole Angolans. (For an exploration of the contradictions that this threw up, read José Eduardo Agualusa’s Nação Crioula, a novel in which the character of Gabriela Santamarinha is based, I suspect, on Dona Ana Joaquina.)

Large-scale colonial settlement in Angola began only after the Second World War, displacing the old creole elite from its position of dominance in commerce and administration. This prompted the children of this elite to turn against the colonial system that had favoured their ancestors, and thus began the current of nationalist thought that gave rise to the MPLA. The class and racial origins of the MPLA were deployed, albeit cynically, by UNITA’s leaders as ideological fuel in mobilising against the state in the Angolan interior. In Luanda, the uprising of 27 May 1977 by the former minister Nito Alves was driven by grievance at what Alves perceived as the domination of the party by a white and mixed-race elite. The MPLA version of events in turn paints Alves as an anti-white racist.

In a half-century of existence the MPLA has had two leaders, both of them sufficiently black to make Angola look like an African country on the world stage. Yet the economic and military underpinnings of power are paler of complexion. Only recently has the Angolan military acquired a black commander in chief, a general who defected from UNITA during the peace process of the early 1990s. The president’s security still depends on a group of light-skinned men, useful because they will never have the popular legitimacy to stage a coup, who are rewarded for their loyalty with mining concessions. Rafael Marques was convicted of criminal libel because he exposed the abusive manner in which these concessions are managed.

The Angolan elite has been good at covering its traces. The fact that the MPLA aligned itself against apartheid in the 1970s and 1980s allowed its leaders acceptance as the good guys, as if South Africa was the only country whose race politics mattered. That ruling class has a longer history, though. And central to that history is the traffic in human life that took place in houses like that of Dona Ana Joaquina.