Sir, - I was delighted to see Garret FitzGerald (January 4th), with his customary fair mindedness, break ranks with official Ireland by acknowledging the debt we owe Sean O'Callaghan for his work as an agent of the State.

I would, however, like to take up Dr FitzGerald's point - echoed by D. R. O'Connor Lysaght (January 6th) - that Sean O'Callaghan's lack of contact with republicans for the last four years renders him uninformed about current IRA thinking.

Mr O'Callaghan was active inside the republican movement for sixteen years, for many of which he was a close and senior colleague of the present IRA and Sinn Fein leadership. He therefore understands this close knit group of people - individually and collectively - better than other political commentator. After he split from them openly, he kept in touch with republican thinking through reading, listening to the media and discussions With journalists and other close observers of Northern Irish politics.

I visited and spoke often to Sean O'Callaghan precisely because his political analysis was so acute and his predictions so accurate. Here is just one example. On the evening of February 9th, 1996, I arrived at an Anglo Irish conference just as the news came of the bombing of Canary Wharf officials from both governments were in a state of shock and disbelief. I was, I think, the only person present who was not surprised for weeks Sean O'Callaghan had been telling me and anyone who would listen to expect a bomb in London in mid February. - Yours, etc.,

40 Pope's Lane,

Ealing, London W5 4NU.