Common Purpose, a secret society?

I was sent an interesting link the other week about Common Purpose being a 'secret society' that manipulated future leaders of the public sector.
Common Purpose is a training scheme for leaders in civic society, both future leaders and established ones.
BBC Radio Five Live recently covered the organisation after critics branded it a 'cult' and 'brainwashers'. Apparently Common Purpose has had lots of these kinds of insults levelled at it and it's staff have also received threatening letters because of the work that it does.
I'm a graduate of Common Purpose. I attended their Frontrunner programme in the summer of 2008. I met some really interesting people, talked about some big issues and learned a lot about leadership.
I wasn't brainwashed during my time there and there was no specific agenda pushed on us - especially not any sort of 'pro-European' agenda as the BBC article alledges. The only agenda we had pushed on us was that we could be a positive force for change in society. I don't think that's a bad thing to be discussing?
The work that Common Purpose does is very beneficial. Yes, the courses are not cheap but that's because of the quality of speakers they get at the events and they are also very well run - you get what you pay for with most training and conference events. The people I met were drawn from every walk of life, some from business, some from charities, some still studying and the debates were very interesting and fun.
The 'Chatham House' rules are necessary because in some of the sessions people are very frank about what they are discussing or guest speakers are revealing some very delicate details about situations they've had to deal with.
Perhaps Common Purpose has more work to do to make its mission clearer and to try not to come off as 'elitist'? Certainly without my time at the Frontrunner programme I wouldn't have the confidence to work on some of the projects I currently am working on or put myself forward to become a trustee for Mencap Liverpool.
So, Common Purpose - a 'secret society?'. I think not. But if they ever send me a cloak and a secret handshake in the post I'll let you know.