This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
Withnail and I
Withnail intended for Uncle Monty to rape Marwood
Withnail is gay while Marwood isn't and he came on to Marwood at some point in the past and was rejected. He feeds his uncle Monty the bullshit story about himself being the one who rejected Marwood as a defense mechanism. Withnail attempts to punish Marwood for rejecting him by telling Monty that Marwood is an active homosexual in exchange for the cottage knowing that Monty will probably come up there and try to rape Marwood.
Specifically, Marwood is most definitely the Doctor, or possibly the eighth Doctor's son (Given their family resemblance). This, of course, makes Withnail also a Time Lord by association.
There was a cartoon Doctor Who Expanded Universe thing in which Richard E. Grant played the Doctor, with a personality not altogether unlike Withnail's. Also note Withnail's "synous nicotine based" technobabble. He must be a Time Lord too.
They're actually all the Doctor. The film is taking place in the head of the Eighth Doctor as he lies dying and preparing to regenerate. He meets a possible next incarnation (Grant) and is also attacked by an alternate version of himself (Griffiths was rumoured to be the planned Eighth Doctor if the original BBC series had continued) trying to become real by 'having' him. Not wanting either alternative, he shaves his head, puts on a leather jacket and heads off to Manchester to become Christopher Eccleston.