New evidence revealed at the inquiry yesterday suggests that the British army's secure radio system failed on Bloody Sunday. This suggests that no specific order was transmitted to the Parachute Regiment to mount the operation in which they shot dead 13 people in Derry's Bogside.
The revelation came during a highly significant day at the inquiry which also heard about a bizarre campaign of harassment of a key witness by the army, and a call by lawyers for an investigation into possible suppression of vital evidence 30 years ago.
Evidence given by a local radio amateur, Mr James Anthony Porter, who tape-recorded police and army radio transmissions on the day, directly challenges a core finding of the Widgery tribunal, which carried out the first official inquiry into the shootings in 1972.
Lord Widgery's report stated: "The order for 1 Para [First Battalion, Parachute Regiment\] to go in and make arrests was passed by the Brigade Major to the Commanding Officer 1 Para on a secure wireless link, i.e. one which was not open to eavesdropping."
However, Mr Porter asserted yesterday that several years after Bloody Sunday British officers told him the special encryption equipment they had on the day was out of operation for technical reasons.
How Mr Porter came to hear this appears to be a curious example of a campaign of official harassment rebounding sharply on the harassers. Now aged 81, he told the inquiry yesterday how he was called to attend the Widgery inquiry in Coleraine only on the very last day of its hearings, March 14th, 1972.
There he was taken to a private room where he was interviewed by a number of "very hostile" tribunal staff, who were joined by Lord Widgery and an army officer.
The Widgery inquiry had transcripts, but not actual tapes of the radio messages. Mr Porter said that when he offered copies of the tapes to Lord Widgery, chairman and sole member of the tribunal, the judge said: "I am tired of hearing about your tapes ad nauseam, and this inquiry is over", or words to that effect.
Mr Porter was not then called to give sworn evidence before Widgery. He revealed yesterday that a few days later he was stopped by an army patrol and photographed.
"My photograph was then posted in a montage of wanted people supplied to all army checkpoints around Northern Ireland, and the caption \ was 'unsympathetic'," he said.
"It meant that every checkpoint I passed through I was arrested,brought to the nearest army post, searched and held for usually anything up to four or five hours - not only me, but my family and anyone who was in my car."
Soldiers searched his house on numerous occasions, and this treatment continued for five years, from 1972 to 1977. But during this period many army officers got to know him and became very friendly.
The topic of Bloody Sunday invariably came up, and the officers volunteered the information that the army's encryption device on that day was "an enormous piece of equipment which took two men to lift".
"It was also a heavy consumer of electric current, and on Bloody Sunday it had run down the battery of the radio car in which it was located, in Waterloo Place just outside the Bogside.
"So the radio car was out of commission during the period of time that the troops entered the Bogside on Bloody Sunday," said Mr Porter. He said this information was volunteered by the officers because by that stage "it was not ever envisaged that there was going to be another inquiry".
Yesterday also, Mr Barry McDonald QC, acting for a number of families of Bloody Sunday victims, asked the inquiry to explore whether there may have been "concealment, destruction or disappearance" of British army photographs and cine-film of Bloody Sunday.
Mr McDonald has formally requested the present inquiry to hold an interlocutory hearing on these issues.
The inquiry continues today.