DEPLORING the state of Heathrow has become a favourite City sport. At a dinner last Monday night, top deal-makers from an American bank cursed the airport and its queues.

“I’m there at 7am twice a week, and always the security is a nightmare. I hate it,” moaned one.

Heathrow’s snarl-ups have an importance beyond disturbing the digestion of highly paid men in suits. Their effect on the economy, and on the City in particular, is cited by the government as the chief reason why the airport should expand, with the construction of a third runway to the north of the existing pair.

The new strip, which will not open before 2020, is fiercely opposed by locals and environmental campaigners. Londoners say they will bear the brunt of the one-third increase in flights, while green groups say there will be an inevitable increase in harmful greenhouse-gas emissions.

Ministers say such objections, while valid, do not outweigh the potential economic damage from leaving Heathrow as it is.

Ruth Kelly, the transport secretary, has supported the expansion. “If nothing changes, Heathrow’s status as a world-class airport will be gradually eroded, jobs will be lost and the economy will suffer,” she said.

Antiexpansion groups have so far steered clear of the economic debate. But now Hacan (Heathrow Association for the Control of Aircraft Noise), the main antiexpansion lobby group, with about 10,000 members, is planning to change tack and challenge the business argument for more runways.

“In the past we have not tackled the economic argument, which has left us fighting with one hand tied behind our back,” said John Stewart, Hacan’s chairman.

Hacan has commissioned CE Delft, the respected Dutch transport and environmental consultants, to probe the economic claims made to support expansion. The report is likely to be launched early next year, but The Sunday Times has spoken to its authors in advance of publication.

First, the case for expansion. Most of the pro-aviation arguments advanced by Kelly and others, in particular the CBI, use for their basic material two reports from Oxford Economic Forecasting (OEF).

In 1999, ahead of an expected white paper on aviation, OEF was asked by the government and a coalition of airports and airlines to examine the issue. It found that aviation Plane speaking: protestors are vigorously opposing Heathrow’s plans for another runway contributed £10.2 billion to GDP and directly employed 170,000.

Seven years later, OEF revisited its report. Aviation’s contribution had increased to £11.4 billion, with 186,000 directly employed. OEF also noted the broader effect on the economy: tourists arriving by air contributed £12 billion, and 55% by value of the UK’s manufactured exports to countries outside the EU went by air.

Proponents of a new runway say that without it, the UK will become a backwater, with more and more traffic bypassing it to go to rival European hubs where space is available.

As Heathrow’s network dwindles, international businesses will go where better transport links are available. Richard Lambert, director-general of the CBI, recently said major financial institutions would desert the City if Heathrow was not expanded.

But Bart Boon, consultant at CE Delft, said this argument ignored the obvious. Over the past decade, London’s economy has enjoyed impressive growth, and the City has become the world’s financial capital – all without a third runway.

“The frustration that business experiences with Heathrow – the queuing for security, for example – has nothing to do with runways. That is just about the efficient running of the airport.

“The evidence is that despite Heathrow having been in effect full for nearly 20 years, business people have continued to come here. It is ridiculous to think that they will suddenly stop,” said Boon.

CE Delft’s analysis will point out that other factors – language, life-style, education, and the availability of the right professional skills – are more important in determining London’s success as a financial centre.

“When you look across Europe, what you find is that these same arguments – that traffic will go elsewhere, that the economy will suffer – are used everywhere to justify new runways. You end up with a kind of arms race where the different capitals are competing against each other.”

Aviation has proved to be of use in stimulating young economies, rather than more mature ones like the UK, Boon said.

“Aviation itself as a driver of economic activity is relevant when you are building up an economy, as has happened in Singapore, for example, or is happening in Dubai at the moment. But the UK is already an established economy. Heathrow will remain a big airport even if a third runway is not built.”

Leisure, rather than business travellers, account for the majority of passengers using Heathrow.

“If you do not expand capacity you might end up pricing some leisure travellers out of Heathrow, but you will not price business travellers out any time soon,” Boon said.

Stewart said London should not be afraid of this.

“I think we should be honest about this and say that it is the more affluent travellers we want coming to the capital anyway.”

Unsurprisingly, the aviation and tourist businesses see things differently. Flying Matters, a coalition of airlines, trade unions, airports and other related businesses, will say this week that without new runways in the UK more than half a million new jobs in the tourism sector will be lost. The figures are based on World Travel and Tourism Council forecasts that predict the number of tourists coming to the UK will grow from the current 32m a year to 82m a year by 2030.

CE Delft’s report is also likely to include criticisms of the original OEF reports. Four years ago Berkeley Hanover Consulting, which was asked by a group of local authorities to examine the issue, said the government had consistently overstated the economic benefits of Heathrow and failed to calculate the full cost of dealing with its environmental problems.

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