Julian Ogilvie Thompson, who has died aged 89, was a pillar of South African business as chairman of the mining giant Anglo American – and a pioneer of post-apartheid change as a trustee of the Mandela Rhodes Foundation.

Anglo American was launched as a gold mining venture in Johannesburg in 1917 by Sir Ernest Oppenheimer, with backing from the US bank JP Morgan & Co. In 1926 it became a major shareholder in the De Beers diamond company founded by Cecil Rhodes, and in later years it expanded into South African consumer businesses and as an international producer of platinum, copper and coal.

Ogilvie Thompson joined the company in 1956. He became the personal assistant and protégé of the then chairman Harry Oppenheimer, Sir Ernest’s son, and rose through the finance side to join the board in 1970 and serve as chairman from 1990 to 2002.

He also chaired Minorco – a group of non-African and non-diamond mining interests also controlled by Anglo and the Oppenheimer family – which he merged into the parent company in 1998 to create one of the world’s largest natural-resources conglomerates.

Tall and imposing behind large-rimmed glasses, Ogilvie Thompson – known to colleagues from his initials as “Jot” – was an intellectual with anglicised manners and aristocratic British connections. He presided with aplomb and political sensitivity over an empire that touched every part of South African economic life during a turbulent era.

One profile called him “a model of British understatement”. It was always his aim to avoid confrontation, but the steel core behind the relaxed exterior also provoked Harry Oppenheimer’s son Nicky, the group’s deputy chairman, to describe him on one occasion as “very large and very difficult”.

Ogilvie Thompson’s challenge as chairman was to achieve amicable relations with Nelson Mandela and the incoming ANC government while also protecting Anglo against radical threats of break-up, nationalisation or asset confiscation – part of the rationale for transferring de Beers’ diamond trading operations to Switzerland and later, as part of the Minorco merger, moving Anglo’s primary listing to London.

After retiring from Anglo, Ogilvie Thompson was a founder trustee from 2003 to 2020 of the Mandela Rhodes Foundation – an initiative based on an agreement between Nelson Mandela himself and the Rhodes Trust to provide postgraduate scholarships (more than 600 to date) and leadership development programmes for young South Africans.

Mandela himself saw the project as a way to “close the circle of history”, utilising the colonial wealth of Cecil Rhodes to address the legacies of apartheid. Among many contributions, Ogilvie Thompson was instrumental in persuading De Beers to donate the company’s historic Rhodes Building as a headquarters for the foundation.

Julian Ogilvie Thompson was born on January 27 1934 in Cape Town to Newton Ogilvie Thompson – an advocate born in the Cape Colony who served as chief justice of South Africa from 1971 to 1974 – and his wife Eve, née Wiener.

Julian was educated at Bishops College in Cape Town, where he was senior prefect, captain of athletics, a 1st-XV rugby player and multiple academic prize-winner. He went on to the University of Cape Town, and from there as a Rhodes scholar to read PPE at Worcester College, Oxford.

He enjoyed grouse-shooting and golf; when in England, he was often to be found at White’s club and, in the summer, at the opera.

Julian Ogilvie Thompson married, in 1956, Tessa Brand, daughter of the 4th Viscount Hampden – whose great-grandfather, the 1st Viscount and 23rd Lord Dacre, was Speaker of the House of Commons. Tessa’s elder sister Rachel, widow of the author William Douglas Home, was the 27th Baroness Dacre. Tessa died in 2020 and Julian is survived by their two daughters and two sons.

Julian Ogilvie Thompson, born January 27 1934, died August 11 2023