Full story: https://www.comedy.co.uk/news/story/00000357/kenneth_williams_new_revelations/
This new book really does look quite fascinating.
See Amazon product listing
[p=http://www.play.com/Books/Books/4-/15412656/Born-Brilliant-The-Life-of-Kenneth-Williams/Product.html]
Indeed. Any/many new Carry On anecdotes apart from the ones that were in his published diaries and letters? One of the highlights of his letters was his description of being seated beside a brandy-drinking, chain-smoking, reminiscing Yootha Joyce on a plane ride from Heathrow to Manchester and back.
He used to start some letters with a whole paragraph about the grammar mistakes of a friend's previous letter! 
What a character.