The Anatomist, By Anthony Sampson

As a student at Oxford, Anthony Sampson was taught by JRR Tolkien, not yet famous as the creator of The Lord of the Rings; he was tutored by the detective writer Michael Innes; he went to seminars given by Lord David Cecil and John Bayley; and he attended lectures delivered by Wallace Robson, Nevill Coghill, Kenneth Clark and CS Lewis. It is difficult to match that in today's Oxford, or indeed any seat of modern learning in the world.

It was a splendid grounding for a man who was to develop into one of the more thoughtful and intellectually gifted British journalists of the past 50 years. Sampson's seminal Anatomy of Britain, written when he was only 33, had a major impact on a generation; his newspaper reports, columns and books set agendas and influenced the decision-makers – particularly on apartheid South Africa, perhaps the major theme of his life.

Anatomy made his name (and gives a title to this autobiography, written before he died two years ago and finished by his wife, Sally). He was to return to it again and again, but by the 1980s he was, as he acknowledges, anatomied-out. He had said most of what there was to say in the first book.

Anatomy was, in retrospect, a remarkably precocious and daring exercise for a young writer. Sampson's inquiring mind had become intrigued with the mysterious and shadowy way decisions in Britain were taken. So he set out to answer the question: who runs Britain? The Establishment, of course. But who exactly was the Establishment, and how did it work?

In a remarkable bit of investigative journalism, Sampson decided to find out. He wrote to 200 top people, from Cabinet ministers to bank chairmen, industrialists, scientists, academics and tycoons, expecting not even to get a reply. It was the story of the emperor's clothes. The supposedly closed world of Whitehall civil servants, the City, the BBC, the Bar and the universities almost fell over themselves to talk to him, astonished that anyone should even think of them as secretive or shadowy – or even powerful. They were as interested in the question Sampson posed as he was. Harold Macmillan, then prime minister, who "provided a kind of caricature of the establishment as a network of interlocking institutions and families", immediately responded with an invitation for a drink and a chat.

The result, written for young people who "wanted to understand the strange world they were entering", appealed as much to a sophisticated, professional audience, and features on reading lists today. It was a book of its time – the Establishment never survived Thatcher's Britain – but reads as freshly today as 40 years ago.

Sampson's interest in South Africa had begun much earlier, sparked by one of those odd little accidents of history Sampson recorded in a charming little book, Drum, which was published in the mid-Fifties and became a cult book for aspiring journalists (including me) in the Sixties. An oddball fellow-student at Oxford, Jim Bailey, the wealthy son of a South African Randlord, started a "new Negro periodical". Drum was intended to provide an alternative African voice and a bit of black culture in the increasing darkness of apartheid. It might have remained an eccentric's dream if Bailey had not offered his old Oxford mate £50 a month to come out and edit it.

Over three years Sampson turned Drum into a real voice of opposition, building a legendary team of young journalists and photographers who set the tone for black journalism in South Africa to the present day. He commissioned Nelson Mandela's first serious political writing, but remained sceptical of him: "he seemed to me too flashy and vain", his rhetoric "too formal and stilted, full of anti-colonial clichés". He only changed his mind some years later when he covered the famous "treason trial". Mandela waved at him from the dock and Sampson, without thinking, replied with the ANC clenched-fist salute. There were always rumours that Sampson was the secret author of Mandela's historic trial speech, but he insists his contribution was no more than "a few suggestions about the style and presentation, which were mostly ignored". At least one myth is intact.

Sampson wrote about many other things, including excellent books on the oil industry, the arms trade and even his gypsy grandfather. He served his time as a gossip writer, became a prolific columnist and polemicist, and even served on the North-South Brandt Commission as editorial advisor. He was still writing when he died of a heart attack at 78, and still with a great deal to say.