just reading my way through Manda Scott's Boudica books (really enjoying them) and although she makes it clear that there is no written history of the British tribes at that time, except that written by the Romans, she has made an excellent story of a society where men and women were able to be equal as warriors or dreamers, and where grandmothers were greatly respected and listened to - yes, I know it's unlikely, but it's fun to think about! - and leadership could descend through the female line. Where have we gone wrong? 
Well done, Mary Beard!