The leaking of the Department of Foreign Affairs internal memo of a conversation with Prof Mary McAleese will probably be dismissed by encrusted cynics as political hardball.

Cliches about all being fair in love and war, big boys' rules, the blood sport of politics and testing in the cauldron of a political campaign will be spouted out. But this analysis cannot blind us to the reality behind the leak; great damage has been done to the State.

The immediate impact was on Prof McAleese, as the leak was clearly designed to damage her presidential ambitions. A telling effect was also produced in the reaction of Mr Derek Nally. His judgement and instincts have been called into question and it appears that he and his adviser, Mr John Caden, could not seem to agree on the same line.

In the longer term, the damage to either Prof McAleese or Mr Nally is likely to be inconsequential. Prof McAleese may emerge unscathed and is likely to be elected anyway on current form; Mr Nally is not likely to be elected. There will be no deep and lasting effect on the public good no matter who is elected.

But there is potentially deep and lasting damage caused to the way this State can conduct its day-to-day business in relation to Northern Ireland.

The Department of Foreign Affairs has had its staff travel for some years among all the players in Northern Ireland. Since 1985, it has had the Maryfield Secretariat fulfilling the role set up under the Anglo-Irish Agreement. People talk to officials on the basis that their conversations are secret to the Government for which the officials work.

These are no mere social conversations. They can be highly significant briefings or they can be opinions helping to build up a picture of the lie of the land in Northern Ireland affairs.

In my short time as a relatively junior official in Foreign Affairs, I did not work at any length in the Anglo-Irish division. But I learned from people there that conversations with players in Northern Ireland were always secret; sometimes because they were dangerous to the point of people's lives being at risk if their contents were disclosed.

Now we have a memo of such conversations being leaked by some player of hardball. Why should any person in Northern Ireland speak again to an official of the Irish Government and trust that the conversation will be kept secret? Can they even be asked to do so? Could this have been the purpose of the leak?

This is not the first leak from Foreign Affairs or from the Irish Government. There was the important leak of a pre-Framework Document text a few years ago where a Garda investigation produced no culprit as far as we know.

Yes, that undermined a negotiating position. Yes, it was serious. But in this case, the danger and the anxiety are much more personal to all those who have confided in Irish Government officials. The drafting of theoretical structures for negotiation can continue; it takes only a little to seal people's mouths and to undermine confidence.

Spare a thought also for Ms Dymphna Hayes, the writer of the memo, who must somehow continue her job as a servant of the State. How paradoxical to have inferences about her inability to report a conversation being bandied about, while she is applauded for her professionalism and reliability from those willing to exploit her good work for what is but fleeting political advantage. And who then challenge Prof McAleese to sue her.

To the leaker: great job. Instant, veiled fame, a sort of anonymous notoriety. If you are a civil servant, shame on you, a disgrace to the very title of your permanent and pensionable position.

If you are a political personage or a handler, what you did displayed stupid recklessness and your utter unfitness for any political role.

If you are a mole, we had better be very careful. Whoever you are, I hope you're caught, even as I guess you won't be.

Oliver O'Connor worked in the Department of Foreign Affairs from 1983-86. He now works in financial services in Dublin.