Well! Shame really that a thread like this brings out the most sanctimonious, the most patronizing, the most dog-eat-dog attitudes of cyclist-against-cyclist!
I'm not sure whether the epithet of 'hairy Neanderthal' applies to me, although I don't see why I should take it as an insult. I have a lot of respect for the much-maligned Neanderthals, what I know of them, from what more recent anthropological studies have revealed. And I am certainly hairy. Indeed, a lot of us are hairy, if we aren't alopecia-sufferers.
Enough of that. I'm not going to join in sermonizing, saying 'do this' or 'do that' or 'go to CM' or 'don't go to CM'... Just relate some of my own thoughts and observations. I used to think of CM as a gathering of cyclists: indeed for me it became a sort of social thing, with joining several others for a meal after an hour or two of it. But alas! the social bit of it is now behind me, as far as I am concerned. And it looks a lot more like a demonstration than a gathering. Let me describe my last turn-out, back in 2008. I was on my own; I was actually in London for another reason, I didn't go specially for CM; I just found the time to pass by the mustering-place under Waterloo Bridge.
I lasted all of five minutes on the ride. Somewhere south of the river (can't exactly remember where) there was a group surrounding a cabbie, bullying and threatening the driver. I didn't see what the driver had done, but I didn't see any signs of injuries or damage. No, they may have had a good reason but they were hassling and taunting (and maybe frightening) this driver, spoiling for a punch-up.
I stopped and watched this little scene from a distance for all of - maybe - ten seconds. Then I made my mind up. I turned my bike around, crossed over to the other side of the road, and pedalled my way the hell out of there.
I haven't been to a CM since. I'm not likely to, not now.
So: as I said I don't want to sermonise. I don't even want to speculate, on whether I was right or wrong in my decision. But I'm open to others' ideas.