I think there are one or two who are younger than 40 i.e. Zoe Loftin (Mellisandre) I believe she told someone (I think Debz_g) that she was about 18 or so when she played Melli. Also Pickle was played be David Learner, which here's a little bit about him, but not his age though http://www.virtualcity.de/englishtheater/dlearner.htm