Sir John Woodroffe (aka Arthur Avalon) was an early 20th century writer who explained and defended tantra as a respectable system of mysticism. The following excerpt is from the review by

Colin Robinson of a book about Woodroffe (Sir John Woodroffe, Tantra and Bengal); an interesting paralell is made between the cases of Woodroffe and HPB. I have added highlighting to a few sections of the quote.

"The most thought-provoking topic of the biography is the working relationship between Sir John Woodroffe and the Indian tantric scholar Atal Bihari Ghose (1864 - 1936), a disciple of Siva Candra. Taylor argues that Ghose was the person whose particular assistance Woodroffe mentions in his explanation of the name “Arthur Avalon”. She presents evidence that the mastery of the Sanskrit literature of Tantra, which is evident in the Arthur Avalon books, is actually due to the expertise of Ghose, not of Woodroffe; that although Woodroffe studied Sanskrit, he couldn’t actually read the language fluently.

"Taylor develops a picture of Woodroffe as an upper class amateur whose was familiar with earlier (often hostile) writings in English about Tantra; and who was able to play the role of a scholar due to the under-acknowledged work of Ghose and other Indian associates.

"After I read this criticism, the thought came to me that this is exactly the opposite of a charge levelled against such esoteric writers as Helena Blavatsky, Gerald Gardner and Carlos Castaneda. Each of these writers has been charged with dressing up his or her own concepts as the doctrine of a mysterious teacher or secret community. Sir John Woodroffe, by contrast, stands accused of letting a secret (or semi secret) community do nearly all the work.

"If we accept the accusation, does it detract from the value of the books themselves? Or does it, rather, confirm their status as the authentic expressions of a mystical tradition?"

Source: http://home.pacific.net.au/~ferment/sirjw.html

So what is our answer to the question at the end? It seems that no matter whether there were particular spiritual teachers backing HPB, or whether her work was mostly based on her own research and experience, she deserves a great deal of credit and is worthy of the high esteem Theosophists bestow on her.