A high-ranking British officer suggested to his colleagues that the rules regarding when soldiers open fire should be "modified downwards" on Bloody Sunday.
Lieut Col James Ferguson, commander of the 22 Light Air Defence Regiment in January 1972, made the suggestion at a conference of army commanders in Derry two days before Bloody Sunday.
In Derry's enclosed built-up spaces "one shot was all that it might take for everyone to believe they were coming under fire", he told the Bloody Sunday inquiry in London.
The meeting was called to discuss arrangements for the civil rights march that weekend, when British paratroopers killed 13 men.
With the prospect of gunfire from either unionists or the IRA being "possible", he asked if there were any plans to tighten the rules over when soldiers were allowed to return fire.
"I thought it was likely that at some stage during the proceedings there would be a shooting.
"In these circumstances, and in a built-up area, it would very difficult for individual soldiers to know who was shooting and from where," he said.
"One shot was all that it might take for everyone to believe that they were coming under fire.
"It therefore seemed sensible to me to ask if there were any plans to modify the rules of engagement."
He said he thought the rules could have been tightened so that the decision on when to fire would be reserved for officers.
Lieut Col Ferguson, now retired, said the suggestion met with a "negative" response and the idea was not developed or discussed further.
He recalled becoming "very conscious of the political significance" of the march after talking to the Northern Ireland prime minister, Brian Faulkner, and his wife at a Stormont reception on January 21st, 1972.
Mr Faulkner asked if everything was under control for the march and then "reiterated more strongly that he hoped everything was under control", Lieut Col Ferguson recalled.
Mrs Faulkner, now Lady Faulkner, said there could not possibly be any repetition of the violence which marred the Magilligan march, a week before Bloody Sunday.
At Magilligan British paratroopers were caught on camera in violent clashes with civil rights marchers. - (PA)