As that list indicates, he took an interest in broad political and economic power structure. But what a mere list cannot convey is that Sampson saw power as personal, so his books often read like series of interlocked biographies — of arms merchants, oil company executives, etc., according to the theme of each. He was a biographer and personal friend of Nelson Mandela.
Furthermore, the personal was for Sampson also the psychological, even the psychoanalytical, as this passage from The Money Lenders shows:
"[Bankers] seem specially conscious of time, always aware that time is money. There is always a sense of restraint and tension. (Is it part of the connection which Freud observed between compulsive neatness, anal eroticism, and interest in money?)".