Pieter Willem Botha, the public face of apartheid in South Africa through the 1980s, died overnight from a stroke at the age of 90.

Botha’s legacy is a mixed one. When he first replaced the hard-line John Vorster as prime minister, he seemed to represent a new, more liberal generation in South Africa’s National Party. A number of the most obnoxious features of apartheid were reformed, and Botha famously told his country’s whites that they must “adapt or die”.

But the fundamentals of the system were not changed, and western opinion was unimpressed. Some felt that a warmer western response early on would have encouraged greater progress, and the then British and American governments pledged themselves to a policy of “constructive engagement” with the apartheid regime.

In 1985, Botha’s “crossing the Rubicon” speech was expected to herald new reforms. I remember vividly the wave of optimism in the west at the time, which raised the hope that a peaceful transition to majority rule was still possible. But expectations were dashed with a fresh state of emergency and a refusal to negotiate with the black majority.

That in turn led to increased sanctions and international isolation.

Tensions between reformers and conservatives divided the National Party, and Botha was already seen as out-of-touch when ill health provided the excuse for his resignation in 1989.

His successor, FW de Klerk, went on to dismantle apartheid and usher in majority rule, for which he shared the Nobel peace prize in 1993. Without the small steps that Botha had taken, however, the larger steps of de Klerk might not have been possible.

History will give Botha credit for starting his country on the road to reform, but hold him to account for his lack of courage in following the path that he himself recognised as inevitable.