I like Alison - she is a kind and generous person with a very sharp mind. However she is not the living embodiment of the megalith-building tradition (I am) and she is just really clutching at the latest results from improved dating techniques to stimulate debate. I am fairly certain that *all* the mounds were made in 'imitation' of natural hills. Probably at that time the particularly fine hill specimens had myths attached that said they were made by previous generations of giants.