From Sahaja Yoga Encyclopedia

It is stated in the Puranas that the Adi Guru Dattatreya worshipped Mother along the banks of the river Tamasa. Tamasa is the same as your Thames and He Himself came and worshipped here. And the Druids, those who had the manifestation of the Stonehenge and all that, originated from that time, in this great country of Shiva or the Spirit. (Shri Mataji Nirmala Devi 23 July 1983)