Chris O'Dell's book, "Miss O'Dell" is a great source of information, particularly on George and Ringo. I think it's a much better book than Wonderful Tonight as it covers those same years at Friar Park but in more detail.
Miss O'Dell:
"The four of us [Chris, Pattie, Ringo and Harry Nilsson] sat around , snorting coke and chatting happily for an hour or so before Pattie and I headed back to Friar Park with our little packet of cocaine.
That night George, Pattie, and I drank Scotch, snorted coke, and played pool in the game room off the main hall." (1973) p. 234
"But ...