Some interesting quotes on why Westcott resigned all his positions within the Order:
"It had somehow become known to the State officers that I was a prominent official of a society in which I had been foolishly posturing as one possessed of magical powers - and that if this became more public it would not do for a Coroner of the Crown to be made shame of in such a mad way."- W.W. Westcott
"Or, as Aleister Crowley more picturesquely put it, the authorities 'intimated to Dr Westcott that he was paid to sit on corpses, not to raise them; and that he must choose between his Coronership and his Adeptship'. Westcott thought that someone was talking, although he had no idea 'who it is that persecutes me'."- R.A. Gilbert, Revelations of the Golden Dawn
It seems to me, reading these accounts, and knowing how Mathers tried to oust Westcott with the revelations of the forgery of the Sprengel correspondence, and later paranoia about Westcott mobilising a rival group against him, that Mathers may have planted Westcott's Order documents where they were uncovered by public officials. It may have been yet another attempt to remove the only rival he had for Order leadership (Woodman being dead), which was successful in this case, since Westcott was forced to resign. It is not surprising then that Westcott told Yeats, some three years later, "you have a mad man for chief". Many people comment on the fine line between genius and madness, and many others talk of the magical genius of Mathers (which I am prepared to admit), but it does seem that, in many cases, I am forced to agree with Westcott's assessment.