Does Alastair McGuckian, founder and director of the multi-national company Masstock, which employs more than 4,000 people worldwide think that his colleagues might be surprised by his latest business venture? The sunlight glitters off the diamonds which encircle the face of his eye-catching gold watch, as McGuckian considers the question and then laughs. "I don't think they'd be surprised by anything I do," he says simply, adding by way of explanation, "Irish farmers just don't go into the desert and start farming."

Masstock is a huge agri-industry, which revolutionised agriculture in the Middle East and Africa, by selling what are essentially farm packages: putting in place a full cycle of production from irrigation and fertilisation of the land to planting crops, or establishing dairy herds, through to the processing stage.

Now McGuckian's latest business venture is The Ha'penny Bridge, a musical which he has written himself and which will premiere in the Cork Opera House tomorrow, and runs there until March 18th. Running international farm packages and writing a musical which is set in 1922 Ireland, focusing on the love story between Dubliner Molly and Englishman George, do make quite incongruous opposites.

"I try to stay out of the eye of the media," McGuckian says, who isn't in the mould of businessman about town: when not travelling the world, he spends most of his time at one of his homes in France. Recently, himself and his wife, Margery, have been spending "about a third of the year in Ireland".

In recent years, he has given virtually no interviews since he does not need to promote his phenomenally successful business, and is quite happy to keep his private life private. While he is clearly anxious to put the wheel of the media behind The Ha'Penny Bridge, there is also a sense that he is downright uncomfortable with any interviews which don't focus solely on figures and agricultural policy. "I hope I don't sound too strange," he admits uneasily at one stage, and then looks as if he wishes he hadn't uttered the comment at all.

Unlike many globetrotting businessmen who engage in communal social activities to bond abroad, such as golf, McGuckian chose to eschew the lot for the laptop and the piano. "Music has always been my way of relaxing, both listening and playing." He has been playing piano since he was a boy, and says he showed a certain amount of talent, which was encouraged by his teacher who hoped he would give more time to it.

Did he ever consider that he could have had a career in music? "I think it could have been a possibility, but I have no regrets about my career in business - although I think I could have been doing what I'm doing now, with the musical, earlier."

The idea for The Ha'Penny Bridge descended on McGuckian at about the same time the bombs were dropping during the Gulf War. It's a love story between an Irishwoman and an Englishman against the backdrop of the Civil War. "I'd describe it as a musical extravaganza," he explains. The show is directed by Cathal McCabe and stars Barbara Brennan. "I think it's a show for people who like musicals. It's not an opera, it's not straight theatre - it's a full exciting piece of entertainment, with drama, laughter, music, and romance."

Then he says, "There are ups and downs in business life. I'm used to putting products before the public. And I have a chance of being more pragmatic about it all than most people. This isn't really my career. But if it's a washout, everyone will be disappointed, including myself."

With a cast of some 40 people, and a theatre which holds 1,000, there's clearly a lot of punts being spent on this production. Where is it coming from? McGuckian won't answer this question directly, although it's a fairly obvious bet that, in addition to writing the music, he has come up with most of the money himself.

"I've always managed to get funds for whatever I wanted to do," he asserts briskly. Putting on a musical you've written yourself rarely happens beyond the amateur dramatic scene, and at one level, McGuckian's Ha'penny Bridge is bound to be perceived as a type of vanity entertainment, comparative with vanity publishing, before anyone even sees it. But whatever the outcome, it must take some guts and confidence to expose yourself and your creative work so openly, when you are known in an entirely different kind of business altogether.

He's shown himself to be a person of idiosyncratic character who was never going to be happy trotting around the communal corporate obstacle course of the golfing green. The pity is surely that he didn't pen a modern political musical, starring the young, singing, dancing Cecilia Ahern instead of Barbara Brennan. Perhaps that'll be the next one.

The charity premiere of The Ha'Penny Bridge in aid of addiction centre, Tabor Lodge, opens at the Cork Opera House tomorrow, and runs until March 18th.