British Press Awards reporter of the year Sheila McNulty said she knew about Lord Browne's private life – but that it was her job to concentrate on the allegations of mismanagement at BP.
McNulty won both reporter of the year and specialist writer of the year for her four-year enquiry into the workings of BP.
It followed a huge oil spill in Alaska in 2002, caused by BP and also centred on an explosion at one of the company's oil refineries in 2005, in which 15 people died.
In the wake of these revelations, Lord Browne announced in January that he was planning to stand down this summer, 18 months earlier than expected.
Immediately after Tuesday's revelations, Browne revealed that he was stepping down with immediate affect – thus forfeiting benefits estimated at around £15 million.
Speaking from Houston, Texas, McNulty told Press Gazette: "I would say that it was our relentless coverage over four years of BP's US problems – which has culminated in a grand jury inquiry – which brought him down.
"After the Alaskan oil spill and the explosion in Texas that left 15 people dead, the FT's coverage really uncovered the real story underneath the BP PR image.
"I had been told that he was gay, but it really was irrelevant to whether BP had business problems."