Third Heathrow runway ‘a costly mistake’

He said the report had underestimated passenger growth at the West Sussex airport and was unrealistic in its assessment of the challenge of controlling levels of pollution at an enlarged Heathrow.

Mr Clarke, 70, a former non-executive director of the engineering group Weir, added: “If this was a decision being taken by the board of a commercial company, it seems unlikely that Heathrow would be chosen, as similar economic returns can be delivered at Gatwick for a lower capital cost, more quickly, and — on a range of parameters — at lower risk.”

The Government has indicated it will make a decision on which option to back by the end of the year with most commentators expecting that Heathrow will be favoured. But Stewart Wingate, chief executive of Gatwick Airport, said: “Introducing real competition between airports has been one of the great successes of recent industrial policy.

“If expansion at Gatwick is given the green light, the benefits of competition will reach even further.”

However, a Heathrow spokesman said: “The Airports Commission confirmed that Heathrow delivers ‘more substantial economic and social benefits than any other short-listed option’ ... a third runway would hand Britain a huge advantage in the global race for jobs and growth.”