A one-time chairman of the Northern Ireland Civil Rights Association said today he noticed an "obvious" change in British army policy on the eve of Bloody Sunday.
Mr Jimmy Doris said the conduct of troops at a demonstration in Co Tyrone on January 29th 1972 showed that a conscious decision seemed to have been taken to prevent marches taking place at all.
And he said he assumed it was a result of Unionist Party pressure being applied at the time by the Joint Security Committee - chaired by Ulster Unionist deputy leader MrJohn Taylor two days earlier.
Mr Dorisalso told the tribunal in the Guildhall, Derry, that no blamed attached to either NICRA or the Derry Civil Rights Association for what happened that day - in contrast to the findings of the original Widgery probe into the deaths.
He said he did not believe the organisers had sought assurances from the IRA that the march would be trouble-free.
"It is something I would have disagreed with completely. I disagree with paramilitarism. If one had approached them it would have been attempting to give them status within the community."
His claims, however, were in contrast to those of another leading NICRA figure Mr Kevin Boyle, who told the Inquiry yesterday he believed assurances had been sought and received from the IRA.
Mr Doris did not attend the Bloody Sunday march but was on the ground when a Tyrone Civil Resistance march was to have taken place from Dungannon, Co Tyrone, to Coalisland.
He stated: "The route of the march was blocked off by the security forces. In view of this the march made its way onto disused land, I believe an old railway line, but the march was blocked again by the RUC.
"This march was different from any march I had been on before. It seemed obvious to me that there had been a change in policy on the part of the army.
"Before marches had been allowed but names and photographs were taken of the marchers such as in Belfast where numerous NICRA organisers were prosecuted and sentenced to imprisonment.
"It seemed a conscious decision had been taken to prevent marches taking place at all.
"I assumed that this was as a result of Unionist Party pressure that was being applied at the time by the Joint Security Committee," he said.