Where do the over-50s go to network?

Over at GREEN on behalf of a client we are looking at how we can use social networks to bring together men in the over-50s demographic and to be honest we are struggling.
The obvious starting place was Facebook and I’ve even asked the question on my Facebook account on where to find the over-50 users. But the answers so far have been of little help.
Clearly there are Baby Boomers on Facebook – thank you Neville for your observations – but they are very difficult to access as you can’t search Facebook by age, at least not so far as I can see.
There are some dedicated Boomer social networks like Eons – but they are largely US-centric. Saga has a social network in the UK but it is a bit clunky and when you look into it appears to be a dating agency for wrinklies.
I can’t find anywhere where there is a serious debate addressing the issues surrounding men’s health – possibly because men don’t like discussing their health. However, it does seem to me there is a gap in the market here – particularly in the UK.
Any thoughts and advice are welcome.