9. "I'm Only 749!"
While this exchange between Maren and the recently captured Doctor in part two is brief, it's a key example of the humour and personality that Tom Baker managed to inject into his performance.
Maren: Doctor! You have but a little time left. Will you waste it prattling nonsense or confess your guilt? The Doctor: What do you mean I have but a little time left? Maren: Before you die. The Doctor: But I'm only 749. Life doesn't begin until-
The flippancy in Baker's delivery is endlessly entertaining. Of course, the early mentions of the Doctor's age are always to be taken with a pinch of salt, as the Doctor was known to tweak the truth even before River Song came up with her now well established rule. What makes this exchange so fun is the glee in the Doctor's eyes during this exchange. The novelisation of The Brain of Morbius finishes the Doctor's thoughts by ending the phrase "life doesn't begin until 750!". Whether or not the Time Lords really use this expression or not remains to be seen. If so, the Doctor is now way,
way past it anyway.