Recently came upon a quite intriguing passage in a letter from HPB to Sinnett.
She wrote to him:
"As for Mr. Hodgson he may yet write one day with his own hand the following, now precipitated by me as far as I can put myself in rapport with him.
In India I was a fool—in the West I have become a donkey. Theosophy is alone true—and S.P.R. is an old monkey. 
Now this is a first attempt. But I swear had I dugpa proclivities I could forge by precipitation a letter which declared by experts as his own hand writing would lead him to the gallows. And I have spoilt it by passing the pencil over it. I had some respect for them for their earnestness, truthfulness, and honesty at first; I have now nothing but contempt for their asinine wickedness and conceit."
 An imitation of Hodgson’s writing precipitated in blue pencil by H. P. B.—ED.
This passage, including footnote, you’ll find in Letter LIV on p. 132 of The Letters Of H. P. Blavatsky to A. P. Sinnett
(London: Unwin, 1925)
My questions are:
1) Is this an authentic letter?
2) Does it still exist?
3) If authentic, what can be deduced from it?
4) Was it ever used in any of the controversies around HPB’s writings to support certain positions regarding the writing of the Mahatma letters?
5) Especially, did Harrison use or acknowledge the letter in his reassessment of the Hodgson Report?