Gatwick has been valued by a leading economic consultancy at £1.33bn-£1.73bn, compared with the £2bn+ estimate from owner BAA. Frontier Economics made the estimate in December in a report for three of Gatwick’s biggest customers - easyJet, Virgin Atlantic and TUI Travel - so the valuation may now be even lower given the downturn in traffic since then. The three commissioned the report to try to ensure the airport was not over-priced, so that they are not hit with unnecessarily high charges or hampered by reduced investment following its sale.

An easyJet spokesman said: "The last thing we want is for someone to do as [BAA owner] Ferrovial has done. Ferrovial’s stewardship has been awful and we do not want to pay for the sins of the past." He added that the airlines were also interested in sealing long-term deals, guaranteeing the numbers of flights with a new owner "to give them revenue certainty".

In November, easyJet won the right for a judicial review of the regulatory process that allowed BAA to impose what the airline called an ‘exorbitant increase’ in Gatwick charges. News of the lower valuation follows the announcement by the Competition Commission that BAA must sell three of its seven UK airports because of competition concerns. The sale of Gatwick is already under way but BAA must also sell Stansted and either Edinburgh or Glasgow airports within two years.

BAA, owned by Spanish firm Ferrovial, said the sell-offs may be "impractical in current economic conditions". It is giving the three remaining Gatwick bidders another month until 30 April to arrange finance for their bids.

The remaining bidders are: Global Infrastructure Partners, owner of London City Airport; Lysander Gatwick Investment, comprising Citigroup Infrastructure, Vancouver Airport Services and John Hancock Life Insurance; and the Manchester Airports Group, owner of Manchester, East Midlands, Humberside and Bournemouth airports, with Canadian infrastructure fund Borealis.