"Second to the Right, and Straight on till Morning"

[Xavier Pan]

Is it true that Barrie took the direction for Neverland from a letter by Stevenson in which the author of 'Treasure Island' explained to him how to get to Samoa? I first heard of this theory in a radio programme celebrating the 100th anniversary of 'Peter Pan'. However, I have read all the letters by Stevenson to Barrie – I think they are 6 in total – and I have not found any reference to this fact. Thank you in advance for your help. 

[Xavier Pan]

As far as I have found out, Janet Dunbar and Lisa Chaney refer to this fact in their books. Maria Tatar also provides an explanation on the location of Neverland in the chapter "Come Away, Come Away" of her centennial edition of 'Peter Pan'. However, it was Barrie himself who first mentioned this letter by Stevenson in 'Margaret Ogilvy': "His directions were, 'You take the boat at San Francisco, and then my place is the second to the left.'" Has any of you ever read this letter? I would very much appreciate it if you could give me some information about its content. I have read all the letters by Stevenson to Barrie and I have not found this particular one. Thank you in advance.