We know now after many years of seasoned viewing that each Doctor has their beginning, middle and end.
The Third's start in life was largely down to the actions of his past self- sentenced to exile on Earth even after doing the right thing by calling in the Time Lords to assist in bringing about the end of The War Games, with the TARDIS rendered unable to travel off world unless those very same Time Lords needed him to on their behalf.
He'd even been forced to get a proper job of sorts as a scientific advisor to UNIT, & acquired a Cambridge-educated lab assistant/companion in the shape of Liz Shaw.
Like many a disgruntled employee, his relationship with his late great boss Brigadier Lethbridge-Stewart could fairly be described as mutually tetchy in its early phase, even though they had met before.
DOCTOR: Lethbridge-Stewart? My dear fellow, how nice to see you again.In time a mutual respect would develop, even if the Doctor didn't necessarily approve of the military mindset- as in his first dealings with the Silurians. Or should that be Eocenes?
MUNRO: He knows you, sir.
BRIGADIER: But he can't do. Look here. Can you hear me? Who are you?
DOCTOR: Don't you recognise me?
BRIGADIER: I'm positive we've never met before.
DOCTOR: Oh, dear. Oh, I can't have changed that much, surely? Oh, I must see what they've done to me. Can I borrow, can I borrow a mirror, please? Thank you. Oh, no! Oh, no. Well, that's not me at all. No wonder you didn't recognise me. Oh, that face. That hair. Oh, I don't know, though. I think it's rather distinctive, actually. Don't you think? No, you don't. Oh, anyway, I'm tired. All this exercise and exertion. It's been too much. Have to get some sleep now.
BRIGADIER: Now, just a minute. Wake up, man. Listen to me.
LIZ: What's that?And after Liz came Jo Grant.
DOCTOR: The Brigadier. He's blown up the Silurian base.
LIZ: He must have had orders from the Ministry.
DOCTOR: And you knew?
LIZ: No! The government were frightened. They just couldn't take the risk.
DOCTOR: But that's murder. They were intelligent alien beings. A whole race of them. And he's just wiped them out.
LIZ: I know.
They too would share many an adventure until she met the Welshman of her dreams, having developed into quite the scientist despite the initial scepticism of her friend & colleague.
JO: But it really is the dawning of the age of Aquarius.Exit Jo, enter Sarah-Jane Smith! Not to mention humanoid spuds the Sontarans.
JO: Well, that means the occult. Well, you know, the supernatural and all that magic bit.
DOCTOR: You know, really, Jo, I'm obviously wasting my time trying to turn you into a scientist.
JO: Well, how do you know there's nothing in it?
DOCTOR: How? Well, I just know, that's all. Everything that happens in life must have a scientific explanation. If you know where to look for it, that is. Excuse me.
JO: Yes, but suppose something was to happen and nobody knew the explanation. Well, nobody in the world, in the universe. Well, that would be magic, wouldn't it?
DOCTOR: You know, Jo, for a reasonably intelligent young lady, you do have the most absurd ideas.
So began Season Eleven of Doctor Who, The Time Warrior serving as an introduction to Pertwee's last stand as the Third Doctor. The curtain began to fall on this day 41 years ago, when on May 4th 1974 the first episode of Planet of the Daleks was broadcast, and over 10 million viewers watched the Third take his latest companion on a trip to Metebelis Three, via a stop at a rural meditation retreat.
Without a giant rolled-up newspaper to swat away the arachnid natives of the planet, his efforts to stop them proved fatal. As they had for one Professor Herbert Clegg before him!
There's something very special just turned up in the post at UNIT HQ, too.
BRIGADIER: Benton.In what we could view as a foreshadowing of things to come the dandy almost literally faces his own mortality, or immortality depending on how you view the regenerative process so neatly described by the Ninth Doctor -''Time Lords have this little trick, it's sort of a way of cheating death.''
BENTON: Sorry, sir. I didn't see you there.
BRIGADIER: What do you want?
BENTON: Well, this package, sir. It's just arrived by express post. I thought it may be urgent.
BRIGADIER: Well, for the Doctor or for me?
BENTON: Well, that's just it. It's addressed to the Doctor or Brigadier Lethbridge Stewart or Captain Yates or, er, Sergeant Benton. It's from South America, sir.
DOCTOR: What, from Jo?
BENTON: I reckon so.
DOCTOR: Well, let's take a look. Oh, no, wait a minute. I've got a better idea. Er, Mister Clegg, would you like to tell us what's inside this package?
CLEGG: This has come a long way.
BRIGADIER: Yes, of course, from the Amazon. Sergeant Benton just told you.
DOCTOR: Brigadier, please.
CLEGG: From beyond the stars. Could it be a meteorite? Oh, it's beautiful. A gemstone. A blue jewel.
BRIGADIER: Lord, not that stone of yours?
DOCTOR: The crystal from Metebelis Three. Thank you, Mister Clegg. Let's take a look, shall we?
DOCTOR: Well, there's only one thing to do now.So we know that in this case, as with the Doctor's past few bodily/personality overhauls, death is not the end. But when the final curtain arrives for him he takes it stoically, before being given a helping hand to finish off his latest renewal of body & spirit.
BENTON: Well, what's that, Doctor?
DOCTOR: I must look into the crystal myself.
BRIGADIER: Isn't that rather dangerous? I mean, look what happened last time.
DOCTOR: I'll bear it in mind, Brigadier.
BENTON: Er, Doctor?
BENTON: Well, wouldn't it be best for me to have a go first? I mean, I'm expendable and you're not.
DOCTOR: Well, I'm already responsible for the death of one man, Sergeant. Thanks just the same.
CHO-JE: The Doctor is alive.Right you are, Cho-je..........
SARAH: No, you're wrong. He's dead.
CHO-JE: All the cells of his body have been devastated by the Metebelis crystals, but you forget, he is a Time Lord. I will give the process a little push and the cells will regenerate. He will become a new man.
CHO-JE: Of course, he will look quite different.
BRIGADIER: Not again.
CHO-JE: And it will shake up the brain cells a little. You may find his behaviour somewhat erratic.
SARAH: When will all this happen?
CHO-JE: Well there's no time like the present, is there?