Billionaire property developer Liam Carroll is believed to have amassed a stake of some 3.2 per cent in Aer Lingus at a cost of more than €35 million. Arthur Beesley, Senior Business Correspondent, reports.

Mr Carroll did not comment when asked last evening about his investment in the airline, which is his third significant stake in a listed Irish company.

Already the owner of a 29.5 per cent interest in food group Greencore and a 29.8 per cent stake in ferry operator Irish Continental, he is believed to have been behind the purchase of 17 million Aer Lingus shares on Wednesday when the stock closed at €2.06 that day. The shares finished yesterday at €2.054.

The identity of the vendor from whom the shares were acquired is not yet known.

Equally unclear are reasons for Mr Carroll's entry into the scene at Aer Lingus, which suffers from habitually poor industrial relations. The airline does not pay a dividend, has no plans to do so, and has no significant property interests. Landbanks held by Greencore and Irish Continental are the presumed target of his stake-building in those groups.

Aer Lingus had no comment last night when asked about the identity of its latest investor.

If Mr Carroll holds onto his Aer Lingus shares for the long-term, as he has done with previous investments, it could have the effect of reducing liquidity in an already illiquid stock.

Among Ireland's wealthiest developers, Mr Carroll has never made any public comment on any of his stock market investments or on any part of his wider business empire.

Other Aer Lingus shareholders include Ryanair, whose 29.4 per cent stake dates from its failed takeover attempt at the time of its flotation in 2006, and the Government, which retained a 25.4 per cent shareholding after the initial public offering.

Ryanair has submitted its appeal of the EU Commission's decision to block its takeover of Aer Lingus to the European Court of First Instance in Luxembourg, the EU's second-highest court. Aer Lingus has separately indicated that it will appeal to that same court a Commission ruling that it cannot force Ryanair to dispose of its stake in the airline.

Other shareholders include the Aer Lingus employee share ownership trust, which owns 14.4 per cent of the airline. Businessman Denis O'Brien owns 2.3 per cent.

The latest information for Mr Carroll's main holding company, Zelderbridge, indicates that it had net assets of €779 million at the end of 2005. This is widely believed to be only a partial reflection of his wealth. Zelderbridge now has unlimited liability.