Too late, baby. You've spent your whole life fighting for the other side. Still, nice try.

Like Kate Moss in rehab, like Posh lamenting the fact that she is too thin, there is something startling about a public figure trying to deny all their own hard work.

Like George Best going on the dry. Like Frank Sinatra retiring. Like Imelda Marcos saying that money doesn't really matter (although I'm not sure that Imelda Marcos has ever said any such thing). Like all those ravishing French actresses who rattle on about how looks don't matter. It's the argument against the essence of one's self that is interesting.

Like Danny La Rue saying he'd just never met the right girl. Like rich men competing with each other to see who was born poorest. When we, the audience, hear these things, we have to have a little smile to ourselves, as Podge and Rodge would say. ( Like Podge and Rodge saying that they really love women for their minds. And vowing to give up? forget it, it'll never happen) Because we know the history involved.

The thing is, if you're very famous, you're not allowed to change your mind. In fact, you're not really allowed to change tack, unless you're prepared to suffer in quite a radical way. Like John Profumo going from golden boy to charity worker for, let's see, was it only 50 years?

Like Sinn Féin wearing peace ribbons. Like Elvis playing Las Vegas. Public change is seen - perhaps unfairly - as either risible or just plain sad. Very few people have managed it. Dana and Mary Kenny do spring irresistibly to mind here. Cheers, ladies.

Nerves of steel, is what it takes. But then, celebrities do have nerves of steel.

That's how they got to be celebrities in the first place. As Dusty Springfield once memorably sang, being good ain't always easy, no matter how hard you try.

And the spectacle of a celebrity, particularly a celebrity politician, trying to be good is really startling.

Of course, privately, we all believe that we can change. It's just that the naked light of the communal gaze falls a little harshly on our resolutions. Particularly if we have been in charge of something - a country, say - for almost 10 years.

The thing about Saint Paul was that - and I'm putting this as gently as I can - no one had ever heard of him before he hit the road to Damascus. And after hitting the road to Damascus, he handled all his own publicity. So no one had any idea what he was like before. Saint Paul emerged into the limelight, completely changed, but no one had anything to compare it with. Saint Paul got to explain all of that to us himself. To the political handlers of today, Saint Paul was one lucky, lucky guy.

At the opening of the Understanding 1916 exhibition at Collins Barracks last Sunday, we listened to Bertie. He looked well, and greeted even little children warmly. But it was very hot, and your attention did wander. It was only afterwards, reading the speech, that you came across sentences such as: "Patriots today are people who are at least as fully aware of the needs of their community as they are of their own individual rights? It is real and genuine mutual respect that builds a truly strong society." And it was then that one question sprang irresistibly to mind: Bertie, is that you?

It's not that Bertie Ahern is a bad person. It's just that he looks kind of uncomfortable clinging to the ankles of Padraig Pearse's departing shade. There is no doubt that Bertie's admiration for Padraig Pearse is sincere. But even their best friends would have to say that Bertie and Padraig Pearse are pretty, er, different.

Perhaps Bertie is going to give up parliamentary politics and face bankruptcy by opening his own schools, as Pearse did. Perhaps he's going to hit the Meals-On-Wheels route - can Bertie drive, does anybody know?

Whatever he's going to do, he'll have to do it for a very long time before we will believe it.