The Second Doctor, in 'Tomb of the Cybermen', claimed to be 450 years old.
The Fourth Doctor, in 'The Power of Kroll', claimed to be 750 years old.
The Sixth Doctor, in 'Revelation of the Daleks', claimed to be 900 years old. So far so good, right? I mean, all those regenerations had to go somewhere.
But the Ninth Doctor, in 'Aliens in London', also claimed to be 900 years old.
What the Shakespeare??