The drama which marked the final days of 50 years of unionist one-party rule at Stormont is chronicled in Cabinet Papers released this week in Belfast.
At a tense meeting on March 23rd, 1972, the Northern Ireland Prime Minister, Brian Faulkner, gave a grim Cabinet a report of his crisis talks in London the previous day with British ministers. According to a note on the file, the British Prime Minister, Edward Heath, began by saying he admired the spirit of the Northern Ireland people.
However, the GOC (Gen Harry Tuzo) and the chief of the general staff (Sir Michael Carver) made it clear that "a military solution would mean an escalation of force, whereas what was needed, in the view of the UK government, was a de-escalation".
This was needed, Mr Heath said, "to swing the Catholic community away from those who were using force". It had been necessary, accordingly, to consider political movement.
Mr Heath told Faulkner that the British government would uphold the constitutional guarantee in the 1949 Ireland Act, while a periodic referendum would add a further safeguard.
"It was necessary to consider how the Roman Catholics could be brought back into community life. It was not sufficient just to go on dealing with violence."
He realised that the Stormont government had put forward proposals for enlarging the House of Commons.
But the UK government had decided these were not sufficient to give the "permanent, active, guaranteed role to the minority". The problem remained of how to bring this about.
"If one was going to escape from violence in Ireland, North and South," Mr Heath said, "further action would be necessary. Internment was clearly unacceptable to the Catholic community and also affected the United Kingdom in its international relationships."
There were obvious risks in phasing it out and deflecting the Catholic community from their passive and active support for the men of violence. "It was the UK view that the way to do this would be for Westminster to take over responsibility for law and order."
The firm conclusion they had reached was that there could be no purely military solution. The drain on UK resources had been considerable and there had been a massive interference with Britain's international commitments. In addition, Mr Heath referred to "a noticeable hardening of the sectarian divide" in the North. Internment and the problems it had given rise to were a major factor in this division.
In a final statement, the British prime minister told Mr Faulkner: "The UK government had a situation where they had the responsibility and the blame for what happened as regards internment and on the security front but were without real power. This was a very unsatisfactory situation which was accelerated by the growing financial dependence of Northern Ireland, and the burden was becoming extremely heavy."