Business Opinion/John McManus:The appearance of super secretive property mogul Liam Carroll on the Aer Lingus share register has sparked predicable speculation that he has some grand plan in mind, the upshot of which will be that he gets his hands on some valuable property assets. In this case the assets being the airline's 13-acre head office site at Dublin airport.

Similar theories surround his two other big investments in listed companies of recent years, 21 per cent of Greencore and 25 per cent of Irish Continental Group. Carroll's interest is thought to lie in the former sugar company's sites in Carlow and Mallow as well as land banks in the UK, while his target in Irish Continental Group is said to be the ferry company's substantial lease hold site in Dublin Port.

The trouble with this school of thought is that it is very hard to see how, despite his big holdings, Carroll can engineer a situation at any of these companies which would see him end up with either control or the sites.

On the other hand, those with long memories point to the coup Carroll pulled off at property company Dunloe Ewart which he bought out from under solicitor Noel Smyth.

Carroll took a 25 per cent stake in Dunloe in October 2000 and, for the next two years used his stake to frustrate Smyth who eventually made an offer for the whole company in 2002 to end the stalemate. That offer was withdrawn - in the face of opposition from Dermot Desmond who had bought into the company and set about trying to remove the board - and Smyth ended up selling out to another investor Pascal Taggart, who then sold on to Carroll.

The process was, to put it mildly, Byzantine in its complexity and although it is possible from this distance to see it as some Machiavellian intrigue masterminded by Carroll from start to finish, such an analysis stretches credulity.

In reality, it was far more likely to be what it appeared to be at the time: a three - possibly four-way scrap - in which Carroll came out on top because he was prepared to pay the most. The subsequent longevity of the property boom, which Carroll may or may not have foreseen, is what has made the deal in hindsight look so breathtaking.

While it is possible that something similar could happen at Irish Continental, it is harder to see it transpiring at Greencore and next to impossible at Aer Lingus.

While all three situations share some of the characteristics of the Dunloe battle, only Irish Continental comes close to the same heady cocktail of big egos and bigger cheque books. It is also the only one where the protagonists appear to see value where nobody else does.

Perhaps the best indicator of whether something similar is on the cards will be whether Carroll sets out to frustrate Irish Continental's management in the way he did with Smyth.

It is worth noting, in that context, that to date Carroll has not thrown his weight around at Greencore, despite buying his initial shareholding in July 2006.

That said he only passed the 25 per cent threshold last June and there has not been an annual general meeting or extraordinary general meeting since then.

Carroll's shareholding in Aer Lingus, at 3.5 per cent, is not enough to give him any influence at this stage, and in any case if he wants to disrupt things at the airline, he will have to take his place in the queue behind Ryanair.

On this basis, perhaps the most rational interpretation of Carroll's intentions is that he has used his substantial wealth to put himself in the middle of three dynamic situations which, depending on the circumstances, could go his way and see him gaining control of some attractive property assets.

The more likely outcome though is that some other corporate activity - the chances of which must be high at all three companies - will see him make a handsome return on his investment in three companies.