An interview on BBC Four with Andrew Lycett mentions a Crowleyan incident in the life of Dylan Thomas…
BBC Four: Are there any anecdotes of Thomas’s wild lifestyle that you particularly enjoy?
AL: I think that his time in London just before and during World War II was when Dylan was at his wildest. In one story he is with a friend at the end of a drunken evening with nowhere to go and he says something like, “I’m so bored of sleeping with women who I don’t like”. He just enjoyed going around London pubs and meeting a wide array of people. Although there is one story of him going into a pub and not enjoying who he met there. Dylan once had an encounter Aleister Crowley and he was very cowed by that. He somehow felt that Crowley’s alleged magical powers were not something he’d like to encounter in the flesh.
http://www.bbc.co.uk/bbcfour/books/features/andrew-lycett.shtml