top marks for mentioning Vicky Cummings. Her next book is about east (via England) vs west (via Ireland) influence in prehistoric Wales.
Looking through the replies, it would appear that we are looking at a south/mid Wales thang.
I will be based in south Powys, in Brecon. The county (Breckonshire) has something like 9 stone circles, 4 rows, 40 standing stones and around 50 hillforts.
I've spent the past 3 years or so researching and writing a Breckonshire "TMA", but have now decided it contains too many facts and will make normal people feel sleepy if they try and read it.