The considerable risk of civil unrest in Northern Ireland in 1972 prompted the then Conservative government to put the RAF and navy on standby to attack the Provisional IRA in Derry, according to the former Tory prime minister, Sir Edward Heath.
The SDLP yesterday expressed "obvious concern" at the revelation, in Sir Edward's autobiography, The Course of My Life, that the government had planned to "intervene in any battle that was going on". A spokesman said that the party would investigate the matter further before making any definitive comment.
A spokesman for Sinn Fein said that it was not aware of Sir Edward's disclosure and declined to comment.
Sir Edward recalled that in July 1972, some six months after Bloody Sunday, when 14 people were killed by the British army in Derry, the purpose of putting the RAF and navy on standby was to end the no-go status of the Bogside and Creggan, which were effectively being run by the Provisional IRA.
After the Provisional IRA had resumed its violent campaign in July that year, following a disastrous secret meeting with the then Northern Ireland Secretary, Mr William Whitelaw, which was attended by Mr Gerry Adams, the RUC and the British army launched Operation Motorman on July 31st to clear the nationalist areas of the Provisional IRA.
Ten days earlier, 11 people had been killed and 130 people were injured in Belfast when the Provisionals exploded 22 bombs in little more than an hour.
Sir Edward described having to talk Mr Whitelaw out of resigning over Sinn Fein's decision to leak details of their meeting to the press. After succeeding in this he had said he was "glad he still had William Whitelaw to help deal with what could turn into a crisis". Referring to the Provisional IRA's resumption of violence, Mr Heath said: "At least the IRA had now proved conclusively that they did not want peace."
However, Sir Edward described the night before the launching of Operation Motorman as "one of the worst" of his life. "All of us involved in the decision . . . knew that the Provisionals were capable of organising fierce and bloody resistance to the forces of law and order. We had the RAF on standby and the navy offshore below the horizon . . ."
In the event, the air force and navy were not engaged in "taking over the whole of the Bogside". Despite the deaths of two civilians, Sir Edward described Operation Motorman as "successful", saying that the rule of law, so far as possible, had been restored to "Free Derry".