During Series 3, at the end of Last of the Time Lords, specifically, this is implied. Heavily, but from what I understand Russell T Davies backtracked on it and it was never stated 100% that it’s the case.
He just made it deliberately ambiguous. He did the same with the picking up of the Master’s ring. It may mean something that will come back and be explained, or it may lead to nothing. It’s up to us, and future writers, to decide.
Jack was totally fucking with the Doctor and Martha. Even when he tells the story, he is obviously building up to a punchline.
In “Utopia”, the Doctor mentions the Face Of Boe in front of Jack, and Jack doesn’t say a word about it being his nickname.
Wasn’t the Face of Boe mentioned as being pregnant with “baby Boemina” in one episode? Maybe The Long Game?
I don’t really see how it could be Jack. Jack is a human being with a body, legs, arms and a normal sized head. Meanwhile the Face Of Boe is a giant freaking face, with no body, sitting in a jar, breathing a different atmosphere.
Okay, stranger things have happened, especially in the Who universe (remember that nice lady who ended up as a paving stone with a decent sex life?). And obviously the intention of that scene in “Last Of The Timelords” is that Jack is suggesting he is the Face Of Boe. But I don’t think there’s any particular reason to take him seriously.
Didn’t Jack say that he’d been pregnant once? ISTR he commented “never again”
In *Gridlock *someone (the Irish catman, I think) tells a story about someone breathing the atmosphere, and his head swelling up to giant size. I p[redict a future episode where that turns out to be Jack.