Most Americans  have a mental picture of an oilman. He is rich, expansive, and wily—a step or three up from the trashy Jett Rink character in the film Giant, updated to be more like the canny, globe-trotting, indicted Houston oilman Oscar Wyatt, and occasionally as cool and calculating as former Exxon Mobil chairman Lee Raymond. Maybe, at this point, he could also be a Saudi sheik, with the obligatory billions. But few would have associated the word oilman with an aesthete or aristocrat until Browne came along. He styled himself as a distinctly British oilman: cultured and eccentric, so polished that his ruthlessness was nearly impossible to detect, so forward-looking and intellectual that reporters listened raptly. In some ways, Browne’s persona is one very familiar to Americans, who have endured their share of recent corporate scandals: a sophisticated C.E.O. in a bespoke suit who can converse about anyone else’s business as easily as his own, who can hold forth on topics ranging from hedge funds to Broadway shows to fine art, from philanthropy to a lovely cabernet to the latest novel by Salman Rushdie. This is the kind of leader who gets a pass from the press, at least until disaster strikes.

One look at BP’s headquarters in St. James’s Square and you get it: The building is a monument to impeccable taste and assertive understatement. Nestled quietly among Georgian mansions, the squat, sunlit brick edifice nods to the past, and inside is as spare and hushed as a monastery. A large, contemporary landscape photograph by Thomas Struth and a video projection of moving grasses serve as the only adornment. A stranger venturing in would not necessarily suspect this is the headquarters of a corporation, much less a global oil company. It is as if someone wanted to pretend that BP was something else ­entirely—a thriving nonprofit dedicated to furthering the arts, for example. And John Browne, the anti-oilman, could have been its leader.

Though Browne was an iconoclast in many ways, the security and serenity promised by British Petroleum, as it was then known, must have called to him when it came time to choose a career in 1966. Tea was served every afternoon for decades; until the 1980s, BP survived largely because the government owned half the company, and Her Majesty’s Treasury kept it afloat during rough periods; jobs were deemed to be lifetime appointments. Before then, the company’s holdings were modest, consisting mainly of sites in Iran, Alaska, and the North Sea. But Browne’s father had worked for the firm, and BP was paying for Browne’s schooling at Cambridge. Hoping for advancement in New York, Browne wound up a pipeline engineer in Alaska, which he found stultifying at first and then, as he rose unbound through the ranks, invigorating.

By 1984, Browne—who got his master’s degree at Stanford, also thanks to BP—was group treasurer and chief executive of BP Finance International. Eleven years later, he became the company’s C.E.O. Throughout the 1990s, he made a series of acquisitions that won him enormous praise in Britain and heralded the consolidation of the major oil companies. It seemed novel then that British ­Petroleum grew not by increasing its oil exploration and development but by taking over American oil companies such as Standard Oil of Ohio and Amoco. The BP-Amoco merger was the largest of its kind and launched the company into the big leagues overnight. When Exxon bought Mobil the next year, Browne quickly retaliated by purchasing Atlantic Richfield for $32 billion.

Browne was also, like any great C.E.O., a P.R. genius. In 1997, to the horror of many of his oil-industry peers, Browne admitted in a speech that he ­believed global warming was real. He then hired a San Francisco firm to ­rebrand British Petroleum and come up with a new corporate slogan. The old BP logo was replaced with a green-and-yellow sunburst, and ads suggested that BP now stood for . . . Beyond Petroleum. It was a masterstroke: BP had only $100 million invested in solar power at the time of the renaming, compared with at least $10 billion invested in conventional energy. But thanks to BP’s green logo and green C.E.O., its reputation as a green company flourished.

At the time of Browne’s ascendancy, Britain could claim few corporate stars. The nation had an even stronger antibusiness strain than it has now, and executives tended to keep their heads down, lest they get blown off. It didn’t take long for Browne to be labeled a rock star for his business acumen and for BP’s boundless philanthropy in Britain and the U.S. His fortunes rose with those of his friend and confidant Tony Blair. In 1998, Browne was knighted, and Blair made him a life peer in 2001. The two grew so close that an underground passage seemed to connect 10 Downing Street and the headquarters of BP—which people began to refer to as Blair Petroleum. Browne even supported Blair’s decision to join the U.S. invasion of Iraq. In 2003, when Browne bought half the Russian oil firm TNK for $6.15 billion, in what was the first significant foray into Russia by a Western oil company, Blair attended the signing ceremony. There was the feeling in Britain of a new beginning, or maybe a return to grander days.

Browne was not quite so popular in the U.S., where experience on the ground is more important than a taste for fine art. “They pounded their chests a lot, but they didn’t know how to run refineries,” a former Amoco employee says of the BP executives. Because refineries are among the most intricate and dangerous workplaces on the planet, the old-timers feared that the BP ­executives’ ignorance would compromise safety, especially as BP cut jobs and budgets to reduce redundancy and raise profits for shareholders. (Similar allegations would later take center stage in the Texas refinery explosion lawsuits.) Other executives were skeptical of the hierarchical management structure at BP; they particularly complained about the handpicked “turtles” (named after the mutant ninja variety), who served as interns to Browne and were supposedly fast-tracked to replace other executives. There was also something known internally as the promise: a written business plan that could be used against employees who didn’t meet their projected goals. “They would use it to cut your throat if you failed,” a former engineer explains. Gradually, the company’s culture became less about innovation than intimidation. Fearful of losing their jobs, few spoke up about deteriorating conditions at some of the refineries. Behind Browne’s back, employees nicknamed him the “elf,” an acronym for “evil little fucker.”

Browne had his critics outside the oil industry too. The company was accused of committing human rights violations while building a pipeline in Colombia, and concerns were expressed about North Sea pollution. Greenpeace selected Browne for its Best Impression of an Environmentalist award. Matt Simmons, whose Houston-based Simmons & Co. is one of the largest investment-banking businesses serving the energy sector, was deeply skeptical of Browne’s 1999 prediction that, because of a worldwide market glut, oil prices would never reach $40 a barrel. “There was a vision of unreality in John Browne’s business plan,” Simmons says. “That generally works until you slip up.”

Still, Browne’s  public acclaim at home guaranteed that almost everyone except bitter Amoco engineers would studiously ignore his private life. When his father died of diabetes in the 1980s, Browne moved his mother, Paula, into the top floor of his Notting Hill house. And when Browne moved to Cleveland as a young executive to work on a merger with Sohio, his mother moved with him, and she is still remembered there as a charming escort and an irreverent hostess. She liked to have a cigar after dinner. Where Browne was understated, his mother was lively and outspoken. She was also his most trusted adviser. Browne’s friends and colleagues grew accustomed to a frequent request: “Do you mind if I bring my mother?”

The British press used a bit of ridicule to state the obvious: “He may be the head of Britain’s biggest oil company, but Sir John Browne is still a mummy’s boy at heart,” read one jab. Another publication noted that he collected Robert Mapplethorpe’s photographs of flowers. But as a gay man in the macho world of big oil, Browne had few choices if he wanted to advance. Asked outright by the press if he was gay, Browne was unequivocal in his denial: “You have got the wrong man there.” It was the kind of lie that people in his circle accepted. He had built a global oil company and made Britain a force to be reckoned with. Who cared about his sexual orientation?

Browne had always reserved his greatest passions for—or sublimated them in—his work. It was normal for him to put in 12- or even 18-hour days. “How did a 5-foot-6 guy who was Jewish and gay accomplish what he ­accomplished?” one of his friends asks rhetorically. “John worked night and day.” And when he wasn’t at work, he was serving on the boards of organizations such as the British Museum and the London Business School.

Then Browne’s world was shaken. Paula died in 2000, devastating Browne, who had always been closer to his mother than to his father. Born in Hungary, Paula had been deported to Auschwitz during World War II. Her son was very protective of her, but he also reveled in her. Stylish, cultured, and determined, she instilled in Browne the need not merely to live, but to triumph for those who perished in the Holocaust, urging him to look forward, never back, advice he took as gospel. Thus, several axioms guided John Browne as he matured: Remain silent about your private life, live for the future, and always, always remain in control.