Robert Mabro, the oil academic who helped broker a historic production cut between OPEC and rivals after prices slumped below $10 a barrel, has died. He was 81.

He died Tuesday while on holiday on the Greek island of Crete, according to the Oxford Institute for Energy Studies, the think-tank that Mabro founded in 1982. No cause was given.

While Mabro led the Oxford, England-based institute for more than two decades, his oil industry career extended beyond the role of analyst. In the late 1990s, Mabro served as the go-between in a landmark production deal between Organization of Petroleum Exporting Countries’ members Saudi Arabia and Venezuela and their competitor, Mexico.

Oil prices plunged below $10 a barrel in the wake of the 1997 Asian financial crisis, rocking the economies of crude producers around the world. Yet as they fiercely guarded their own share of the market, mutual distrust among those nations prevented them from cooperating to halt the rout.

A solution began to take shape in January 1998. Adrian Lajous, then head of Mexican state-owned oil company Pemex, met Mabro in Oxford for “leisurely conversation, good wine and, if possible, a touch of intrigue,” Lajous recalled in an article last year in the institute’s in-house journal. The wary oil nations had found the neutral confidant they needed to open a channel for talks.

“Robert Mabro played a key, if unaccredited, role in the secret negotiations that brought together these three countries,” said Lajous.

In a series of meetings and phone calls during the ensuing months, Mabro served as intermediary between officials from Saudi Arabia, Venezuela and Mexico. The diplomacy yielded joint production cuts in late 1998 and early 1999 that by mid-2000 fostered a recovery in the price of crude to more than $30 a barrel.

The success of the deal vindicated Mabro’s witticism that OPEC should change its logo to a tea-bag “because it only works in hot water.”

Mabro, a fellow of St Antony’s College, Oxford, who was honored by Queen Elizabeth when she made him a Commander of the British Empire in 1995, was born in Alexandria, Egypt in December 1934 from Lebanese parents. He is survived by his wife Judy and their two daughters.

He obtained a degree in civil engineering from Alexandria University, and after a brief spell working in Egypt moved to Paris and London to study philosophy and economics. After moving to Oxford in 1969, Mabro developed an interest in oil.

The desire to bridge differences between OPEC and oil consumers was a theme of his life, and a huge challenge back in the late 1970s and early 1980s, when an oil embargo by Arab states and a subsequent shock from the Iranian revolution shook the global economy.

“He is truly an oil man with principle,” Ibrahim Al-Muhanna, an adviser to Saudi Arabia’s oil ministry, wrote in May last year in the Oxford Institute for Energy Studies’ quarterly journal. “He is an intermediary who brings people together free of charge and for the good of everybody.”