Ulick O'Connor's great grandfather, a Young Irelander, was described as an "extreme" man. O'Connor, an upper middle-class Irishman who flits across the social spectrum, still brings a whiff of danger to all his activities

Ulick O'Connor has always been fascinated by personal histories. Many years ago, when he was conducting research for his book, The Troubles, he visited Dublin Castle, sought and was granted access to the police file of his great grandfather, Matt Harris.

What he found therein enthralled him. Even the minor movements of Harris, who had fought with the Young Irelanders during the Fenian Insurrection of 1867, were documented. Speeches given by Harris during the years of revolution and during the subsequent land agitation were faithfully recorded in the copperplate hand of bureaucrats and paid spies.

Harris had even been trailed across the Atlantic on a trip to New York. Detectives shadowed him on board a transatlantic liner, and during his stay in New York even steamed open his post at his hotel.

O'Connor was astounded by the detail in the files: "As I looked at the mass of papers, I thought of the not-inconsiderable bureaucratic energy that had gone into recording the movements and utterances of one man. The lifetimes of a number of persons had been occupied by the task. This is what the colonial system meant. More important even than the welfare of those governed was the task of ensuring that those who opposed the system should be silenced."

Harris was a man of some property, and later served as an MP for East Galway, after it had been decided by Davitt, Devoy, himself and others at an IRB summit in the Hotel des Missions Etrangeres in Paris (in 1879) that "extreme men" might participate in public movements.

Harris, whose story was recounted to O'Connor by his aunt, certainly qualified as an "extreme man". His own father had been hanged at Pallas, Co Kildare in 1798.

Perhaps it is from this side of his family that O'Connor has inherited a healthy and unflinching disrespect for authority and convention. He too has lived in turbulent times and he too has been a dissenting voice.

A writer who shuns the academy, an accurate and objective scholar who insists his books embody an accessible populism, a committed republican during a period when republican views were beyond the Pale -- especially among the native Irish.

An upper middle class Irishman who flits across the social spectrum, mixing a certain nostalgie de la boue with an affinity with burnt-out and functioning aristocrats. All the while he retains a verbal pugilism which, in an era of blandness, is as attractive as it is disconcerting.

In the past O'Connor has written handsomely and well of Wilde and Behan and Gogarty, and of the whole caravan of Irish writers. He has documented the uplifting and dreadful history of our country. But he chose the year 2001 to write, or rather to cause to be published, a book about himself.

It is a move that will have required a certain amount of brass neck in a land of knockers and begrudgers, where the publication of private diaries (as opposed to the keeping of same) is a virtually unknown art form.

"There is no role model for this in Ireland. In Britain people like Byron and Disraeli wrote diaries and more recently Harold Nicholson, Chips Channon and, of course, Alan Clark. But this is the first set of diaries written by an Irishman and published by a British publishing house," says O'Connor.

The cast of characters that populates the pages of the O'Connor diaries is vast. There are so many proper names in this volume that it would scarcely be amenable to full indexation. Politicians, writers, poets, hobos, beat up aristos, drug fuelled rockers and their groupies, serving sports stars and non-playing members of the Pavilion club, actors and actresses, agitators, lounge lizards, fashion designers, drink sodden lawyers and artists all crop up in three hundred or so pages (two more volumes are in the offing).

O'Connor bristles somewhat when I put it to him that, given the lapse of time since the 1970s and given that some of his subjects might be termed minor celebrities, the diaries might be difficult for a young, modern reader to appreciate or even to follow.

"Of course you could follow them, unless you are a fucking eejit," says O'Connor, relapsing into the familiar patois of his native city. As for the suggestion that the cast of characters consists of little known individuals who crossed his path he asks rhetorically: "Who has not heard of John Hume or Gerry Adams or Andy Warhol..?"

O'Connor bristles too, when it is suggested that it is rather strange for an avowed republican like himself to be celebrating in his diary entries a series of wistful afternoons and hedonistic evenings spent in the company of the remains of the Anglo-Irish gentry.

Reciting a list of Protestant patriots as long as the pole that catapulted him to sporting glory many decades ago, he retorts that the Anglos built the great houses generations ago and the leadership to preserve those same houses from the ravages of developers (for the benefit of present and future generations) has come from the same class.

In any case, his fondness for this class has no political overtones, he writes about them as a friend. And for every toff he encountered during the decade of which he writes there are several others who would have come from a very different social background.

The period covered by the diaries stretches from the emergence of the modern IRA to the hunger strikes. Ireland's English Question is a leitmotif throughout, though its presence is not obtrusive.

O'Connor provides an unusual insight into the turbulent politics of the decade. He acted as an adviser to Jack Lynch on northern matters, but later in the period associated himself with the campaign to win political status for the hunger strikers (the book concludes with a coruscating account of the Embassy Riots in Ballsbridge).

O'Connor the republican still admires Lynch greatly. He believes his leadership prevented the IRA (which O'Connor says was essentially a southern organisation in 1970) from re-opening a new chapter of the Civil War in Dublin. A few emotion-charged incidents or wrongly handled moments might have catapulted the Dublin government into deep crisis, he contends.

Firing Haughey and Blaney was "not good for Haughey or Blaney" he says, but was definitely "done for the good of the country". He says that Lynch is deeply misunderstood. Few knew what was on his mind. He had "a certain guile... some might even call it dishonesty."

This sauve qui peut attitude also informs O'Connor's views on the terrible years of 1922 and 1923. As a writer who wrote an impassioned play (Executions) concerning the Free State's officially sanctioned policy of vengeful capital punishment, O'Connor's heart lies with the republicans of that period. But he insists that the vast majority of executions were carried out "under law" and that the "government of the day was entitled to act as it did to end the war".

The contradictions remain. The writer appears simultaneously to side with the "unbroken and unbreakable Fenians" while accepting that out there is a society that demands to be run in an orderly fashion. Perhaps only in the personality of his hero Michael Collins has a fusion of these two concepts been achieved.

O'Connor's family were very much of the Cumann na nGaedhal tradition during the formative years of this state, but it is -- in his view -- a tradition light years removed from that of the modern Fine Gael party under FitzGerald and Bruton.

Upper middle class and cut from a Free State block he might be, but his mother (who was reared in Booterstown) spoke in native Irish till she was 12, while his father (subsequently Dean of the College of Surgeons) acted as a medical auxiliary to republican units in the west during his early years as a doctor.

The other leitmotif to penetrate these diaries is sport. Top class amateur sporting achievement to be precise. As a young man and well into his middle years the author excelled at boxing, athletics and rugby. He played five other sports as well, while taking degrees in philosophy and law and commencing a career as a writer.

Perhaps he was lucky. In those Spartan years it was possible for a gifted amateur to excel at sport in a way that is not possible in the current period of specialisation and ruthless competitiveness. O'Connor was a poll vault champion. He still claims the fastest ever KO to be recorded at the National Stadium and he played rugby for both St Mary's and London Irish.

He was, of course, no shrinking violet, but he accepts that there is little in common between the way sport was conducted in those days and the way it is today when brute physical force is so important and when underhand techniques are the rule rather than the exception.

"Boxing is the one sport which has never got dirty. Perhaps it is because the sport openly encourages the player to give his opponent a good hammering and afterwards obliges both fighters to put their enmity behind them."

The dreadful dialectic that has overtaken top class sport and made it off-limits for talented and committed amateurs perhaps sums up the process that has marked O'Connor's gifted life. For here is a walking contradiction: a 21st century Renaissance man. A sportsman of noted achievements, an historian, a talented biographer and writer, a lawyer, a polemicist, a strutter of stuff in the public arena.

For now, he continues to write and write well, even in a period when publishers embrace the most "appalling bilge" and where "poets multiply like spermatozoa wriggling around without any apparent idea or purpose".

Time was when honest scholarship was required before putting pen to literary paper, but now O'Connor confides with customary understatement that "these people not only have no knowledge, they have a hatred of the knowledge they don't have."

The Ulick O'Connor Diaries 1970-1981 -- A Cavalier Irishman are published by John Murray at £22.50