Alan Butler is British and an engineer by profession and for the past thirty years has been a full-time researcher and writer with a number of successful books to his credit(a). His area of interest is principally ancient civilisations which led to the publication of Civilization One and Before the Pyramids co-authored with Christopher Knight. A critical review(e) of the former is offered by Jason Colavito, a man who only writes critical reviews.
The sequel to Civilization One was Who Built the Moon  in which Butler and Knight offer evidence that our Moon is artificial! Even more extreme is his claim in Intervention that at critical junctures in man’s history, humans from the future have returned to intervene!!
Butler also wrote a book on the Phaistos Disc – The Bronze Age Disc. In it he contends there is support for his 366-degree geometry. The Disc having 30 divisions on one side and 31 on the other, which, with, a calendar alternating 30-day months and 31-day months would result in a 366-day year! Sylvain Tristan supports this idea(d) .
He has only touched briefly on the subject of Atlantis in a number of his books,>but this changed with his 2014 book The Dawn of Genius in which he deals more fully with Plato’s island<. In chapter nine he expresses the view that Plato’s Atlantis story is probably a conflation of a number of historical tales of which the Minoan Hypothesis provides some of the threads. He rejects an Atlantic location as contrary to geology and Plato’s nine thousand years to be archaeologically unsound.
Guy Gervis wrote a positive review of Civilisation One, while a more critical view of Butler is offered by Jason Colavito(b).
In 1999, Butler published City of the Goddess, which deals with Washington, DC’s direct connection with Freemasonry and its veneration of the Great Goddess! Then in 2015 America: Nation of the Goddess will be published. It has been co-authored by Butler and Janet Wolter, wife of TV presenter Scott F. Wolter. We are already informed that among the gems contained in it, is the revelation that “every baseball diamond is actually a temple to the Goddess.” I’m not making this up. Jason Colavito was equally surprised(c).
Sylvain Tristan is a young French researcher who has adopted the theories of Jean Deruelle, who advocated the idea that the Atlanteans were in fact the Megalith Builders of the Bronze Age who left us a legacy of remarkable structures from Scandinavia, along the Atlantic seaboard including the British Isles and on down into the Mediterranean as far as Malta. Tristan also subscribes to Deruelle’s contention that the capital of this civilisation had been located on the Dogger Bank in the North Sea, between England and Denmark.
A second major influence on Tristan’s thinking was the writings of Alan Butler, who among other matters, has argued for the use of 366-degree geometry by the Megalith Builders. Butler wrote the Foreword to Tristan’s Les Lignes d’or, it can be read on Tristan’s English language website(b), while the French text of the book is available online(e).
Tristan returned to the subject of 366-degree geometry in his latest book, Numbers of the Gods.
Tristan has expanded on the work of his mentors in two books.
An interview with Tristan can be accessed on the Internet(a). Unfortunately, his non-fiction output has only been published in French so far, but in 2012 he published, The Divine Number, in English, as a Kindle book(c). This novel is based on a series of secrets associated with the 366-degree geometry of Butler’s research. He introduces the book in a short YouTube clip(d).
Tristan’s idea of a megalithic Atlantis has been heavily criticised by Alain Moreau(f).
(a) https://www.world-mysteries.com/newgw/gw_stristan1.htm (link broken)
(b) The Golden Lines (archive.org)
(e) Tr – PDF Archive (link broken)
(f) False Atlantis (3) Atlantis was not in the North Sea | mondenouveau.fr (archive.org)