Holidaymakers queuing today to pass security checks at one of BAA’s big airports might well feel they could clear up the Competition Commission’s inquiry into the airports operator with little effort. Does joint ownership of Heathrow, Gatwick and Stansted affect the company’s willingness to invest in service, not least security?

It forms only one part of a broader inquiry, but could provide an insight into whether airlines and passengers would benefit from a break-up of the UK’s largest airports operator.

Ryanair reckons a break-up would force rival airports to fight for custom, either reducing charges for airlines, and so, ultimately, to passengers; improving facilities, to improve the experience; investing in customer service; or a combination of all three.

That might well be true, but the issue facing Heathrow, and all carriers which use it, is not price but capacity — specifically the lack of spare take-off and landing slots.

British Airways claims that a break-up would solve this problem, too. If Heathrow and Stansted were competing they would each have more of an incentive to push through plans for extra runways.

BAA counters that as a combined group it has the financial might to fund expansion.

That could be a strong argument were it not for the mob of infrastructure funds lining up to invest in UK assets offering long-term steady returns. The economics of aviation remain compulsive — limited supply, strong demand, and a growing economy.

Just look at the interest in recent airport sales elsewhere in the country — Leeds Bradford was sold to Bridgepoint, the private equity firm, for £145.5 million this year.

The Competition Commission’s study is not a foregone conclusion, but a break-up of BAA in the South East could be to the benefit of both airlines and passengers.

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