A NUMBER of chance events, persistent digging by campaigners, and some dogged legal pressure on archive repositories combined to generate the revelations which - a quarter of a century on - have undermined the report of the British government's inquiry into Bloody Sunday.

Don Mullan, whose book Eyewitness Bloody Sunday is officially published next week, was a 15 year old schoolboy when he was at the centre of events in Derry on January 30th, 1972, and was lucky escape with his life.

Immediately after Bloody Sunday, along with hundreds of other witnesses, he gave a statement to the Northern Ireland Civil Rights Association.

NICRA later supplied all these witness statements to the tribunal of inquiry being conducted by the British Lord Chief Justice, Lord Widgery. The Widgery Tribunal, it has subsequently emerged, took only 15 out of almost 700 of these graphic personal statements into account.

Returning to Derry in 1996, Mr Mullan visited the Pat Finucane Centre where in a "well worn plastic supermarket bag" he discovered the statements, forgotten for more than 20 years.

Around the same time, pressure by solicitors for the relatives of the Bloody Sunday victims had also begun to elicit new documents, memoranda etc relevant to Bloody Sunday and the Widgery Tribunal, from the Public Record Office in London.

Detailed research on all of this material began to point to a significant and previously unexplored aspect of the killings. The Widgery Tribunal report - and the general impression of events had at tributed all of the casualties to the firing of members of the 1st Battalion Parachute Regiment (1 Para) who stormed into the Bogside on foot and with armoured vehicles.

Lord Widgery accepted the versions of the soldiers and their officers that these soldiers came under fire - "There is no reason to suppose that the soldiers would have opened fire if they had not been fired upon first," Widgery, concluded.

But the multiple witness statements examined by Don Mullan (and also available to, but not seriously explored by, Widgery) included many accounts claiming that firing had also come from British army units situated high up on the old city walls overlooking the Bogside.

This focused new attention on experience of a doctor attended the official post mortem examinations at the request of the then Catholic Primate Cardinal Conway.

Dr McClean, who was inexplicably told by the Widgery Tribunal that his evidence was not required at the official inquiry, had established that the trajectory line of the bullets which killed three of the victims was downwards, at an angle of almost 45 degrees. It appeared that these victims, at least, could not have been shot by troops situated at ground level in the Bogside.

This new channel of inquiry led Mr Mullan, and more recently researchers for Channel 4 television news, to the records accumulated by another key witness whose material had also been shelved, or sidelined, by the Widgery Tribunal.

Mr James de Wint Porter, a radio amateur, and member of Derry Citizens Central Council, had made tape recordings of all the army and police transmissions on the fateful afternoon.

He made transcripts and submitted them to the Widgery Tribunal, which chose, however, to discount them on the basis that they had been obtained by the illegal interception" of radio telephone messages.

These detailed transcripts couched in military jargon, indicate clearly that shots had been fired by units other than the Parachute Regiment, based on observation posts on high ground at the city walls.

Mr de Wint Porter's analysis of the timing and content of these radio reports and messages has led him to a reasoned conclusion that some of the first shots fired after 1 Para entered the Bogside came from these observation posts.

While there is no doubt from the many witness statements and even from some of the carefully equivocal conclusions of Lord Widgery himself, that the Paras "ran amok" on the ground, the radio messages support an entirely new theory as to what triggered the uncontrolled bout of firing.

Mr de Wint Porter asserts that the early shots from the city walls, which killed two civilians, "appeared to the advancing Paras to come from the high flats. They panicked and ran amok, opening fire at the people still standing at the flats and around the rubble barricade. In the next 30 minutes they fired in excess of 200 rounds of high velocity ammunition. Eleven more innocent people were shot dead and 13 were injured."

The radio amateur's records also appear to explain an apparent total confusion and conflict of situation reports and commands as between the various senior army officers on the ground.

Lord Widgery chose to consider (and, in the judgment of some researchers, to distort) the significance of the official army log of communications on the day. Mr de Wint Porter's records could at the very least have been used to compare and corroborate, or put, to the test, the army's version of events. This was not done.

Asked why he appears to have delayed drawing attention to his records for 25 Years, Mr de Wint Porter insists. I didn't wait at all. All this evidence has been with Widgery from day one."

He points out however, that the technical nature and minute detail of the communications were such that its significance was not appreciated by Bloody Sunday campaigners and their solicitors at the time.

Now, in conjunction with the witness statements documented; by Mr Mullan's book and the archive material finally winkled out by others, the core significance of this evidence has begun to be apparent.

Taken together, all of this evidence has powerfully reinforced the demand by the relatives of those who died for a full independent inquiry into the events of Bloody Sunday. It has raised yet again the most serious questions about the impartiality and thoroughness of the inquiry headed by Lord Widgery, now deceased.