The chief executive of Heathrow is stepping down only four months after acknowledging that customer service at the world’s busiest airport had fallen to “unacceptable” levels.

Tony Douglas will join Laing O’Rourke, the construction firm charged with a key role in the effort for the 2012 London Olympics, as chief operating officer next month.

BAA, the Heathrow owner, confirmed the move in a short statement to the London Stock Exchange this afternoon.

Stephen Nelson, chief executive, said: "Tony's outstanding achievement for BAA had been the development of Terminal 5, one of Europe's largest building projects, which remains on time and on budget.

"I would like to thank Tony for his tremendous contribution and wish him every success in his new role."

Mr Douglas’s departure comes in the middle of Heathrow’s busiest summer, with as many as 200,000 passengers expected to pass through the airport’s four terminals on certain days.

The 44-year-old took over the running of Heathrow as managing director in 2005 and was promoted to his present role last July, only weeks before the thwarting of a liquid-bomb terrorist plot that aimed to blow up aircraft leaving the airport.

The terrorist attempt sparked chaos at the airport, with queues of passengers stretching outside terminal buildings.

Mr Douglas joined BAA in 1998 and oversaw the construction of Terminal 5, which involved Laing O’Rourke.

Terminal 5 is 97 per cent complete and will be handed over to British Airways in September.

At the time of the terror alert last summer, Mr Douglas said that BAA was doing all it could to deal with passenger volume, but he explained that Heathrow was “not blessed” with spare capacity.

However, this year he admitted that passengers were still having to queue for far too long in departure lounges.

“There is no question that customer service at Heathrow has been unacceptable and at times it continues to be unacceptable,” he said.

Mr Douglas’s career began in 1979, when he joined General Motors as an apprentice.

He will be replaced at Heathrow by Mark Bullock, the current managing director at Heathrow.

Ray O'Rourke, chairman and chief executive of Laing O'Rourke, said: "This very welcome appointment reflects our determination to grow the group strategically and further reinforces Laing O'Rourke's vision to challenge and change the image of construction work."

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