Counsel for five self-acknowledged former members of the Official IRA yesterday opposed the introduction of British security and intelligence material relating to them.
Cameramen were obstructed by a number of burly young men in T-shirts as lawyers representing MI5 and the police left the Guildhall at the end of the day's hearing and were driven away in an unmarked van. The men, who had English accents, refused to identify themselves or what organisation they worked for.
During legal argument earlier, Mr Gareth Purvis, for the former IRA members, said his clients had indicated they would be coming forward to give evidence, but they had concerns about it.
It was openly and publicly stated that they were all members of the Official IRA at the time of Bloody Sunday, and therefore any issues of credibility in relation to them as witnesses were open and obvious.
However, he asked what the purpose was of "trawling through these men's past, bringing up activities in which they were involved before and after Bloody Sunday".
Mr David Lloyd-Jones QC, for a number of soldiers, said the mere fact of a witness's involvement in terrorist activities should be sufficient to persuade the tribunal it could not attach any weight to the evidence of that witness.
But if the tribunal took a different view, it might be necessary for it to know the extent of the involvement, the dates of the involvement and the nature of activities.
Lord Saville said the soldiers' submission seemed to be that, notwithstanding any admissions made, the tribunal needed all the details that might be in the possession of the security services.
Mr Purvis said the soldiers' side was proposing, in effect, a collateral investigation. "They want to trawl up every single event, build up a large ball of mud, and throw it straight at these witnesses," he said.
He said his clients would come forward and state exactly what they were doing on the day in question, and that evidence would be filtered through the evidence of approximately 1,200 other witnesses and all the other evidence the tribunal had before it.
That was the correct procedure to follow, he asserted - not to examine an event the witness was involved in three years before or five years after the event.
Mr Martin O'Rourke, representing another group of civilian witnesses, warned of the dangers associated with the tribunal admitting such material. Once intelligence material was made available, then, whether it was shown to be true or false, the damage was done to the witness.
That might affect his employment, or his right to life, or his social standing. That was irrespective of whether this material was ultimately shown to be categorically untrue.
Mr Philip Sales, for MI5, the RUC and the Metropolitan Police, said clear and objective criteria would be essential if any search exercise was to be carried out effectively.
Mr Sales said the volume of material to be searched to prepare the summaries in relation to specific witnesses "pales into insignificance against the totality of the agencies' archives relating to Irish affairs during the Troubles".
The chairman, Lord Saville, said the tribunal would consider the submissions and rule on the issue as soon as possible.
The inquiry continues today.