Yet this display of confidence, demonstrating that 'Supermac' was unworried by CND's rise, was merely a veneer. For documents newly released by the Public Record Office show that, behind the apparent calm, the Government was shaken by CND and faced a threat that United States troops guarding their air bases in Britain would open fire on demonstrators, with disastrous domestic and international consequences.
At the same time, ministers were planning a secret multi- departmental group to counter the CND demonstrations. It would gain intelligence from within the organisation's hard- line direct-action arm, the Committee of 100, led by the philosopher Bertrand Russell.
For three years, the Government secretly directed every force at its disposal against the organisation, and even contemplated introducing new laws to stop it operating.
The key file covering these events was not released under the 30-year rule and was held over until now. Records from the Prime Minister's office show confrontations coming to a head at the end of 1961, when the Committee of 100 was planning a series of demonstrations at US air bases in Britain on 9 December. Officials at the Air Ministry warned Macmillan on 5 December that while the police were confident they could contain demonstrations at RAF Ruislip, they expected 'more serious problems' at USAF bases at Wellesfield in Essex and Brize Norton in Oxfordshire.
'Nuclear weapons are stored at these stations and a proportion of the aircraft are held at instant readiness with nuclear weapons on board,' the warning said.
'These aircraft and the bomb stores are guarded by armed American sentries. The demonstrators intend not only to block the entrances but also by means of 'commandos' of 30 men and women to invade the airfield and immobilise the aircraft by sitting around them.
'The USAF have made it clear they cannot permit the demonstrators to impair operational mobility. They have said that, if demonstrators persist in approaching sensitive areas and disregard the orders of sentries, the latter will be compelled to open fire.'
The Air Ministry told the Prime Minister it was planning to support the police with 6,000 military guards.
The Government was also using behind-the-scenes legal pressure against CND. The Attorney General's department responded to the Air Ministry warning with plans for search warrants against the organisers, who would be arrested on the eve of the demonstration.
'I do not propose to charge the figureheads like Russell, but the people really behind this,' said the ministry memorandum.
It said there were 'serious political implications' in the threat of US troops opening fire, and suggested asking President Kennedy to instruct his commanders in Britain to obey the RAF officer in charge of controlling the demonstration.'
It is not clear if Kennedy was contacted, or whether the shooting threat was lifted. A note says the next page of the file was removed and destroyed on 7 December 1961.
On 8 December the Prime Minister heard in a note from his private office that the Eastern National Bus Company had been persuaded not to carry demonstrators to the air base, leaving 900 without transport. But it regrets that it could not stop all supporters travelling.
On the same day the Attorney General's plan led to five CND protesters being arrested and charged with incitement to civil disobedience.
The counter-operations meant that the few hundred demonstrators who turned up were easily contained by a security force outnumbering them 10 to one. Early in 1962 the leaders were jailed for periods of 12 or 18 months.
Soon after this the CND women's deputation met Macmillan after Iain Macleod, chairman of the Conservative Party, and the Defence minister, Peter Thorneycroft, advised him to do so.
'It is the initiative about peace that has really captured the people's imagination,' said Macleod. 'I feel it would give a bad impression if the Prime Minister did not meet such
a very strong delegation.'
The Prime Minister went ahead after Special Branch confirmed that none of the women, who were led by former senior civil servant Dame Alix Meynell, and Mary Stocks, a pillar of Government committees and Any Questions, was a communist.
A Home Office file records that the Committee of 100 lost its momentum from this time, and the resignation of Bertrand Russell in January 1963 was 'the biggest blow to their prestige'.
Yet the Government did not let up - it became more sophisticated. By mid-1963, Henry Brooke, the Home Secretary, recommended in the final note in the file that a committee of the police, the Director of Public Prosecutions, the Defence ministries and the Home Office should be set up to co-ordinate responses to any forthcoming demonstrations.
But with hindsight, the crisis was already past. In August 1963 Macmillan signed the nuclear test-ban treaty, and by October had resigned through ill-health. In 1964 Labour returned to power, and in retrospect it can be seen that CND was spent as a political force - apparently without knowing how much it had shaken an already rocky government.