Just a quick post about Mike's use of the name "Williams".
The early days are shrouded in mystery, not least because none of the documentation has been publicly released for general inspection, but we are told in Inside Story that, following Mike's second call to London, on 10 March 1992, "Montgomery wrote to Williams confirming that she and Harrison would look forward to meeting him and his wife, and seeing the diary, in 'due course'".
So Mike appears to have given his correct address otherwise he wouldn't have received the letter, which I assume he did.
In a way which is completely opaque, a meeting was fixed for 13 April 1992 but we are told that, at some point before this meeting, "In a subsequent phone call to Montgomery, Michael Williams revealed that his real name was Michael Barrett". We are not told if this was subsequent to Mike's receipt of the letter or simply subsequent to the 10 March phone call and we thus have no clue at what time he decided to reveal himself to be Mike Barrett (which he supposedly did because he was happy he was being taken seriously).
As he had to provide his contact details to Martin E Earl, who he instructed to obtain a Victorian diary on his behalf, it would have been a bit tricky, and fairly pointless, to have given correct telephone number and address but a false name.