I've just been watching the 2007 Children-in-Need Telethon, 'mini-episode' of Doctor Who entitled "Time Crash" ( see it here, if you haven't seen it yet. )
It details an encounter with the then current, Doctor (David Tennant) and one of his previous incarnations (Peter Davison) and takes place in the period between the Doctor saying goodbye to Martha Jones (at the end of the "Last of the Timelords" episode) and the incident where the Tardis crashes into the 'RMS Titanic' spaceship at the beginning of the Christmas 2007 episode "Voyage of the Damned."
Most of the seven and a half minute episode deals with interaction between the two Doctors, and there's a curious conversation between them that takes place when the subject of the Master crops up:
DT: "Right, Tardises are separating. Sorry Doctor, back to long ago. Where are you now? Nyssa and Tegan? Cybermen and Mara? Timelords in funny hats, and the Master?- Oh! he just showed up again, same as ever."
PD: "Oh no! Really? Does he still have that rubbish beard?"
DT: "No. No beard this time; well.. a wife."
As many of you reading this will be aware, when a gay man who prefers to publicly conceal his sexuality, makes use of a woman to masquerade as his wife or other sexual partner for the purposes of diverting any attention from his otherwise non-heterosexual preferences, the term often used for the said lady is 'a beard' (presumably because, like a beard, she adds some illusion of masculinity to her partner; for simlilar reasons the male equivalent, helping to conceal a woman's secret lesbian persuasion, is known as 'a handbag'.)
So is the Doctor publicly 'outing' the Master? Or since both parties to the conversation are in actuality the Doctor himself, could this be something that has been known to the Doctor for long enough for him to casually mention it to his other self? If this is the case, it begs the question: Why has the Doctor never mentioned the subject when other characters have been present?
Is the Doctor himself possibly gay?
Were he and the Master perhaps lovers at one time?
Now I know this is all supposition, and I'm sure the Doctor Who scriptwriters will never confirm or deny any part of it, but it makes me wonder why they'd put such a blatant clue into the script.
Make your own minds up, but I'll leave you with one final thought: Quite definitely the most effeminate of the Doctor's incarnations was the one played by Jon Pertwee. This particular Doctor was without his Tardis for most of his tenure and found himself exiled on Earth, yet he still found himself meeting up with the Master at least once if not more, when the Master was supposedly travelling the highways & byways of time and space. Did a shared affection maybe draw them together?