There was an unbroken priestly oral tradition going back aeons that was (sadly) invested in a minority. The R*m*ns destroyed this by herding the Celtic druids onto Mona and killing them all. Now we know how the circles (eg) were made - because the craftspersons' oral tradition has continued to contemporary times - but we don't know why they were made - nor how they were laid out.
Guy Fawkes is a minor deity now - at least round here !