Leading members of the campaign - including one who was once arrested under the Prevention of Terrorism Act - have held meetings with officials from the Ministry of Defence and the Foreign Office, and with Ian Soutar, Britain's new ambassador to the Conference on Disarmament in Geneva.
Since Labour's election victory in May, CND's role has changed from that of an outside irritant of government to a valued partner in developing policies. It is hiring an advertising agency to spread the message that nuclear disarmament is still a live issue.
In Parliament, it was behind a submission on disarmament proposals signed by 30 left-wing MPs and presented to George Robertson, the Defence Secretary, as part of his strategic defence review. And, in the next few weeks, CND officials are expected to meet Tony Lloyd, minister for arms control and disarmament.
Most remarkably of all, CND has been invited into the heart of Whitehall to help formulate policy. It has held two meetings, one over tea and biscuits in the office of Richard Grozney, head of the Foreign Office security policy division, and the other at CND's north London offices with Mr Soutar, arranged at his request shortly after his Geneva appointment was announced.
CND was represented at the first meeting, in June, by its chairman, Dave Knight, and its parliamentary officer, William Peden. On the Foreign Office side was Mr Grozney and two other FO officials. A representative from the Ministry of Defence was also present. Political sources described the meeting as "bizarre but ground-breaking".
"We got the impression that Mr Grozney expected the CND people to be hippies and wear sandals, and that the CND people expected the civil servants to be very stuffy - but they got on very well and left understanding each other's point of view a little better," said one source.
The meeting with Mr Soutar was held the following week. It is understood he requested the meeting to establish CND's position and, according to one source, to "ask for advice".
Present at both meetings was Mr Peden, 31, CND's parliamentary officer, a softly-spoken Scot who founded the peace camp outside the Faslane nuclear naval base in 1983. From 1983 to 1987 he was routinely arrested during protests, his phone was tapped and he was held under the Prevention of Terrorism Act for publicising the movement of nuclear missiles. No charges were ever brought.
He refused to discuss the meetings yesterday but he did agree that CND's outsiders have come in from the cold.
"Under Tony Blair's government, there is a new openness and a willingness to discuss fresh ideas," he said. "Doors are now open to us that years ago would have been slammed in our faces.
"After being treated as an enemy of the state, it is nice to be regarded as someone who can make a positive contribution."
Founded in 1958 by, among others, the philosopher Bertrand Russell and the author JB Priestley, CND has always been viewed with suspicion by the security services due to the early support it received from members of the Communist Party, to which it was never affiliated.
Its profile was highest during the 1960s when protests were held at the nuclear research establishment at Aldermaston and during the 1980s when American Cruise and Pershing missiles were stationed in Britain.
However, from a high of 100,000 in 1984, membership has fallen to around 40,000 since the end of the Cold War and the removal of the missiles, prompting a fresh campaign to recruit members and raise its profile.
A week ago, it appealed for advertising agencies to run its campaigns for free. Ten applicants have since been considered and the successful agent will be announced soon.
"We want to raise the issue first, and our own image second," said Louise Edge, CND's spokeswoman. "It has gone from people's minds a little, but we have to remind them that disarmament is by no means complete - there are still thousands of nuclear weapons out there."