IAG chief executive Willie Walsh launched his latest attack on the airport’s capital programme yesterday, adding that allowing third-party operators to run the terminals would lead to better value for both airlines and travellers using the facility.

Now his comments have received the backing of rival airline Virgin Atlantic, albeit with some reservations.

A Virgin spokesperson said: “We agree with Willie Walsh that Heathrow’s track record of delivering capital projects on time and on budget is not good enough.

"That’s why we have called for a Passenger Cost Guarantee; ensuring passengers don’t foot the bill for expansion through higher charges.

“Willie is absolutely right to be concerned about a monopoly at Heathrow - what he fails to mention is that IAG operates more than half of Heathrow’s slots, so there are many routes that are only served by one of his airlines.

"Expansion must deliver a significant increase in airline competition to provide the choice and value that passengers deserve.

"Virgin Atlantic stands ready to play our part alongside other carriers.”