Although he has by now built a massive stake in the ferry company, nobody is sure of his intentions. He is said to be primarily interested in the company's 33-acre site at Dublin Port and isn't prepared to mount a takeover offer of his own. Instead he is reportedly set on building his stake up to 29%, the maximum amount he can own before triggering a mandatory takeover bid.

With his 24.82% stake, though, Carroll has already passed the magic number to block any bid. Under the current scheme of arrangement, a successful bidder must win the backing of 75% of the company's shareholders. However, with the bidders barred from voting on their own shares, he already holds in excess of 25% of the remainder and any prospective new owner will have to play ball with him to win his backing.

With this in mind, you might expect a frantic round of behind-the-scenes horse trading, with Aella and Moonduster currying favour with Carroll. However, neither party says it is talking to him. The only known contact Carroll has made was a bid in August for the Moonduster stake, which was rebuffed. Once Carroll's stake is big enough to dictate terms, somebody's phone may ring, but nobody is banking on it.

"He is that kind of individual, " said one source close to one of the bidders. "He plays things very close to his chest and we have no idea of what his game plan is. It may be the case that he is waiting for one party to walk away and he will step in and negotiate with the other."

"It is a bit of a cliche, but he is quite secretive and we have no idea what he plans to do, " said another source close to the bidding. "He keeps himself to himself and I'm not even sure if he employs any formal advisers. He is one of these guys whose mobile phone is his of"ce."

Carroll's role is also a mystery to ICG's independent directors. Chairing last week's EGM, John McGuckian said: "He doesn't seem inclined to say anything to anybody." McGuckian then wryly added that speculation on the development potential of the Dublin Port might bring other billionaires out of the woodwork.

Carroll is an enigma to many in business world and, along with shunning publicity, is also renowned for his unostentatious lifestyle. Unlike many of his peers, he doesn't spend a lot on snappy suits, reputedly drives a middle of the range car second-hand car and has relatively modest offices. He first came to public attention as the man behind Zoe Developments, which built controversial low-cost apartments in Dublin in the 1990s. However, Carroll has since moved up the value chain and is spending more time on acquiring sites with showpiece development potential.

Although his conduct in the ICG takeover battle is inscrutable, it is hardly surprising, since his takeover of Dunloe Ewart in 2002 bore many similarities to this situation. Carroll quietly built a 29% stake at a time when chairman Noel Smyth was attempting a buyout of the listed property company, but famously never made contact with Smyth, much to the latter's consternation.

"There is no communication. If you can imagine somebody spending 50m to buy into your company and won't spend ten cents on a phone call, " he told a shareholder meeting at the time.

Carroll sat tight and blocked the bid until Smyth sold up to Paschal Taggart, who then promptly sold out to Carroll. A site in the Dublin docklands also played a role in that deal. Smyth outbid Carroll by a mere �50,000 for a 4.1-acre site at Sir Rogerson's Quay in 1996, which he then sold on to Dunloe Ewart. Six years later, Carroll had outmanoeuvred Smyth and the site was "nally his.

With a track record like this, Carroll is likely to be in no hurry to put his cards on the table and is likely to move only when he thinks the time is right.