Said one observer: "You can be sure that all of them will be opposing the Ryanair bid."

But will the ESOT's members . . . almost 4,700 former and current Aer Lingus staff . . . be able to resist the lure of potential tax-free earnings if they decide to ditch Aer Lingus and embrace Michael O'Leary?

The ESOT trustees last week dismissed Ryanair's contention that each ESOT member would be in line for a 60,000 tax-free payoff. In a statement they said that if ESOT members accepted the current 2.80 per share offer, each serving staff member would receive 38,864 on average, while ex-staff ESOT members would be in line for just under 14,000 on average.

There is still some uncertainty as to how many people actually belong to the ESOT.

Some staff members received shares under the so-called Cahill restructuring plan in 1993. That equated to about 5% of the airline. When the company was again restructured in 2001, roughly another 9.9% was made available.

One of the trustees, Greg O'Sullivan, has recused himself from the ESOT as he's also the airline's finance director. Another, Brian Wheatley, the carrier's head of group treasury, retired at the time of the flotation.

So how do they all stack up?

David Beattie Partner, O'Donnell Sweeney Age: 53 Based: Longford Beattie (below) is an old hand with employee share trusts. A partner with Dublin law firm O'Donnell-Sweeney and head of the outfit's commercial department, Beattie was a member of the Eircom ESOT.

He commutes from his Longford home to Dublin. He currently sits on the boards as a trustee of employee share ownership plans of companies including ESB, An Post and ICC Bank.

Beattie attended the High School in Rathgar, Dublin, and graduated from there in 1970, according to school records. He studied law in TCD, obtaining a BA in 1975 and an MA in 1992. A reported lover of the outdoor life, he has been described as a "safe pair of hands" and is recognised as being among the best practitioners in his field in Ireland.

Apart from his extensive work with ESOTs and ESOPs, Beattie also takes a punt on business ventures.

Earlier this year it emerged that he was an investor in a wind farm project, Oriel, in County Louth. It raised 6m in funding from individuals such as GE executive Dan O'Connor and Grafton Group's Colm O Nuallain.

Glen Dimplex founder Martin Naughton also invested in the firm, which is planning an 85m, 250MW wind farm off the Louth coast.

Brian Wheatley Ex-head of Group Treasury, Aer Lingus Age: 55 Based: Dublin Today, Wheatley turns 55. In the past few weeks the accountant has left Aer Lingus and held his retirement party the week of the flotation.

On Thursday he resigned as a director of the trust and was replaced by 66-year-old Dan McGing (above), former chairman of ACC Bank and a Fianna Fail stalwart. The bank became embroiled in controversy after lending millions towards the construction of the upmarket Four Seasons hotel in Dublin.

One well-placed source described Wheatley as an "Aer Lingus lifer", having started work for the airline in the 1970s. He began his career there working in ancillary activities, which covered everything from hotels to subsidiaries such as charter airline Futura, Turkey-based Pegasus, Cara Computers, Irish Helicopters, and not so good investments such as ATS Tooling in Canada.

Described as "serious", "highly regarded" and "diligent", Wheatley was later responsible for selling off many of those ancillary assets.

The ancillary division was headed by Denis Hanrahan until 1990 when he left to head tobacco firm PJ Carroll.

He was also a Bank of Ireland non-executive director.

Wheatley was seen as a "bright young thing", according to one source, but many of his moves within the carrier were virtually lateral as opposed to vertical.

He became involved in treasury functions within Aer Lingus in the mid-1990s, responsible for managing the airline's exposure to financial risks. Part of the work included liquidity management . . . making sure there was enough working capital and cash resources.

Greg O'Sullivan Finance director, Aer Lingus Age: 47 Based: Dublin O'Sullivan will turn 48 next month and joined the airline in the late 1990s. He previously worked with PriceWaterhouseCoopers, where he is understood to have worked after leaving university, and would have been a deputy to the now departed Brian Dunne.

Although described as "extremely competent", he never became a partner at PWC, despite his long tenure there. "He's not one to seek the limelight, " said one source.

Dunne, the airline's chief financial officer, worked alongside chief executive Willie Walsh (now head of British Airways) and chief operations officer Seamus Kearney. Dunne now works as chief financial officer for ACE, the owner of Air Canada.

Walsh was renowned for owning a battered 10-yearold Honda Accord, despite his high-profile job and decent salary. O'Sullivan seems to have a similar trait, driving, according to sources, a car that has been around the block. A keen traveller, he is in the perfect job to be able to indulge that passion.

He is also a music lover and concert-goer.

O'Sullivan has been involved to a minor extent with the activities of the Institute of Chartered Accountants in Ireland. He is also a member of the board of Irish Airline Pilots' Pensions and has recused himself from his role at the Aer Lingus ESOT.

Jean Cashman Cabin crew, Aer Lingus Age: 47 Based: Dublin Cashman might just as easily offer to sort out your pension as serve you a cocktail if you met her on an Aer Lingus flight. The mother of two has worked with the airline for over 25 years and is described as "smart" and well able to handle the financial intricacies that may arise during her work as an ESOT trustee.

And you can expect her to have a firm understanding of how all that money that Ryanair is offering employees will be treated by the Revenue Commissioners.

While working at Aer Lingus, she trained as a tax consultant and worked in that capacity in the inheritance tax section of PriceWaterhouseCoopers. She has also lectured at the Irish Taxation Institute and was active within the Impact union. It is understood that her sister has also worked for Aer Lingus.

Cashman campaigned for changes to the inheritance tax laws and raised awareness of the issue on RTE and in the national press.

Her daughter is understood to have followed her mother's footsteps into the financial business world.

Michael Clair Ground crew, Aer Lingus Age: 48 Based: Shannon Clair's competence in financial matters that may arise before the board of trustees may not be on the same level as some of his colleagues, but he plays an important role.

Also described as an Aer Lingus lifer, he is seen as a "nice guy" and "salt of the earth", according to one Sunday Tribune source. He provides the ESOT with not only a view from the western seaboard, but also an overall picture of how lower-ranking staff might be reacting to offers on the table.

Noel Dowling National organiser, Siptu Age: 57 Based: Dublin From the midlands, Dowling (below) is known to be "dogged", but in all the right ways. He won't pursue issues just for the sake of it, but reliable sources said he will see important ones through. He ran for the position of general secretary in Siptu, but failed to get it.

A heavy smoker described as a "nice guy", Dowling will surely be getting through the cigarettes as he and the rest of the trustees work to fight off the Ryanair bid. He was heavily involved in the restructuring of Aer Lingus in 2001, following the US terrorist attacks. That saw Siptu members accept over 2,000 job cuts and a pay freeze to save the airline. He has also been involved in disputes involving Dublin Bus and the Gama construction workers who were being paid below minimum wage.

Shay Cody Deputy general secretary, Impact Age: 50 Based: Dublin Second in command at Impact, Cody represents cabin crew, pilots and middle management at Aer Lingus.

He is the most likely candidate to succeed Impact's general secretary, Peter McLoone.

Union insiders say the relationship between Impact and Siptu remains somewhat tense, especially on a local level, since 2000, when pilots and cabin crew defected to Impact from Siptu. Although they effectively made the decision themselves, Cody got the blame for the move.

From Dublin, he studied history and politics at UCD in the mid-1970s. He has worked for trade unions since leaving university, first with UPTCS (Union of Professional and Technical Civil Servants), which later merged with LGSPU, the local government union.

Seen as an intellectual, he is described by one insider as "more cerebral than emotional". While you're unlikely to see him glad-handing at conferences, he's not a cold fish, says another source.

Tensions persist between Impact and Siptu, as the former was not fundamentally opposed to the carrier's flotation . . . its members were seen as having most to gain from the sell-off. Other sources say that while tension may bubble under the surface, the two unions are going to be singing from the same hymn sheet when it comes to opposing Ryanair's bid.