Mark Bullock has said that criticism of Heathrow does not bother him; it just motivates him to work harder. This saint-like patience is an important characteristic for a man who has to turn up every day to what has been described as one of the worst places in Britain.

Mr Bullock has the unenviable job of running the world's largest international airport. That would be a difficult task even in a new, purpose-built facility but Heathrow is an ageing airport that crams 68 million passengers into terminals designed to cope with 45 million.

Accidents and mishaps are daily events at Heathrow and even when the airport is trying to improve, things seems to go wrong with alarming frequency - witness the Terminal 5 debacle.

Mr Bullock has been BAA's managing director of Heathrow since 2006, which almost qualifies for long service at a company that has seen numerous senior executives head for the door in the past year.

The departures have included Stephen Nelson, BAA's chief executive, and Tony Douglas, Heathrow's chief executive.

Mr Bullock took over full responsibility for Heathrow after Mr Douglas's departure last year and he was promoted yesterday to BAA's executive committee, which should give him a much greater say in how the company runs its most important asset.

He will be responsible for an investment programme designed to turn Heathrow from the butt of jokes into a world-class facility. This includes rebuilding Terminals 1 and 2 in time for the 2012 London Olympics and pushing ahead with permission for a third runway.

He must also ensure that all the little things that annoy passengers so much are eliminated, such as security queues, broken lifts, broken toilets and take-off and landing delays. Add to this a requirement to wring every penny out of Heathrow to pay down BAA's enormous £17 billion debt and it is clear that Mr Bullock will need stamina.

Fortunately, as a fitness fanatic who rises at the crack of dawn every day to go to the gym, he seems well suited to the task. Before becoming head of Heathrow, Mr Bullock, an accountant, was in charge of BAA's Terminal 5 project.

Prior to joining BAA in 2004, he worked at EDF Energy and was finance director of Exel, the logistics company.