The impending break-up of BAA could lead to the biggest change in the UK's airport infrastructure since the British Airports Authority was privatised 21 years ago. Indeed, potential buyers have expressed interest already in the assets that BAA could be forced to sell after the Competition Commission's inquiry into its market power.

The commission said yesterday that BAA should sell three of its seven airports to end the company's monopoly in the South East and in Scotland. Gatwick, Stansted and Glasgow are likely to be those selected for sale and aviation analysts believe that the new owners could tailor them to better reflect the airlines that use them.

For example, Ryanair and easyJet, the budget carriers, represent 85 per cent of traffic at Stansted and both have repeatedly demanded lower charges. Michael O'Leary, Ryanair's chief executive, has said that proposals to build a multibillion-pound second terminal at Stansted were a waste of money, calling such a building a needless “Taj Mahal”, and has suggested that Ryanair could buy the airport, although this idea has been dismissed by most analysts.

Ryanair and easyJet are willing to co-invest in new infrastructure at Stansted, but only if it meets their needs. That could mean that facilities built at Stansted in the future would be cheaper and more basic.

Gatwick is regarded by many in the aviation industry as the real prize in this enforced divestment process. Four parties - Manchester Airports Group, which owns four airports in the UK; Fraport, which operates Frankfurt; the Singapore-owned Changi Airports International; and Dubai Aerospace - have expressed an interest in buying one of BAA's airports and are likely to be watching the Gatwick process closely. Infrastructure investment funds will also be involved, although Macquarie, which owns Bristol airport, has ruled itself out of future acquisitions.

If Gatwick were to be bought by Changi or Dubai, it could radically alter the use of the airport. Dubai, for example, could persuade Emirates, Etihad and other airlines based in the Gulf to move their flights there, creating a hub for travel to the Middle East.

Heathrow almost certainly will remain owned by BAA, but it is focusing on international, long-haul passengers. The number of short-haul flights operating from the airport is likely to be reduced and those that remain will act as feeders for the international carriers.

James Fremantle, industry affairs manager at the Air Transport Users Council, said: “I don't think passengers should expect immediate changes - this is going to take a long while. We look forward to better services and maybe cheaper fares, but services are the main issue. Passengers want better value for money.”

Scotland could benefit from the sale of Glasgow or Edinburgh, since the new owner would be able to take advantage of the greater space at these airports to increase capacity. Peter Morris, chief economist at Ascend, an aviation consultancy, said: “This might have more of an influence on Edinburgh and Glasgow, where the opportunity to expand and do things differently will be greater than in London. In the South East, it will be more about rearranging the furniture rather than expanding the size of the room.”

However, these changes will take years to come, particularly if BAA appeals against the Competition Commission's final report, which is due next March. The process could also be complicated by industrial action - airport worker unions have criticised a BAA break-up. Steve Turner, national secretary of Unite, said: “Any attempt to break up BAA will be resisted. Our members will not sit back while the market plays games with their jobs and their terms and conditions of employment.”

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