In the previous story (the War Games), the Time Lords (so named for the first time) have finally caught up with the Doctor, and as punishment for meddling in the affairs of lesser species he's exiled to an insignificant little planet (Sol 3 in Mutter's Spiral, or "Earth" to it's inhabitants), had his TARDIS driver's licence revoked, and been forced to "change his appearance". (No mention of "regeneration" here; the term will be introduced in five years time.) From here on in, it's all change.

The first thing you'll notice about Spearhead From Space is that it's in colour. The second is that, compared to earlier (and unfortunately also later) stories, it looks like a million bucks.

Industrial action by studio staff at the BBC meant that the studios at Television Centre and Lime Grove were effectively closed, and the only way to shoot this story was 100% on location and therefore 100% on film. Until the mid-70s video cameras were too bulky to use on location, so what little location work there was on most television drama productions was done on film before being transferred to video tape. This was no bad thing, as video cameras were very bad at picking up lighting subtleties, resulting in a flat, plastic-looking finished product. Of course, you then get a rather jarring aesthetic jump when you cut from a location scene to a studio scene, but film was also horrendously expensive compared to video, so outside of exceptional circumstances, you just had to live with that.

Having said that, it's still not quite cinema standard, even for the time. There are quite a lot of rather clumsy edits, maybe because the ad-hoc, emergency nature of the production didn't leave a lot of time for planning for all the needed footage. The acoustics in some locations are pretty dreadful (mainly echo), which I quite like because it lends a kind of cinéma vérité quality, though I can imagine it drove the BBC engineers barmy: You may complain studio recordings look and sound unrealistic, but it's controlled, standardised, professional unrealism, dammit!

Not only was Spearhead in Space Jon Pertwee's first story but it was also coming after the longest break between consecutive series in the show's history to date. So it was particularly cheeky to keep the Doctor drifting in and out of consciousness in his pajamas for the first episode and a half, but I imagine it got the frustrated viewer coming back week after week for their first proper look at the new Doctor. I suspect it's not a coincidence that David Tennant spent his first episode in a similarly prone and stripey-flannelette-clad state.

If, with the benefit of already having seen him in action, you're not waiting for Pertwee's Doctor, you will barely miss him because the cast are almost without exception quite splendid. Returning character and new regular Brigadier Alastair Gordon Lethbridge-Stewart (the ever-lovable Nick Courtney) is wry, no-nonsense and smart as a whip - a far cry from the military buffoon he occasionally ended up as in the hands of writers who should have known better (looking at you, Terrance Dicks; "he can wear what face he likes" and "pretty sure that's Cromer", indeed!). I'm also in the minority that believes Caroline John as Liz Shaw can do no wrong. A more grown-up and educated female companion for the Doctor (a species not seen since Barbara left in series two) is a blessed relief, and as for her all-too-soon replacement by Jo Grant... well, we'll come to that in due course.

Pertwee is on record as bemoaning the fact that outgoing script editor / producer Derrick Sherwin (seen in a cameo as UNIT's carpark attendant) didn't let him play the part in this first story as straight as he would have liked, Pertwee being known exclusively as a comic actor up to that point. I think with one exception the comic moments are quite appropriate, and in fact have become part of a tradition of post-regeneration eccentricity that persists to this day (eg. fish fingers and custard). However no review of this story is complete without mention of that one exception.

It comes quite late in episode four, so to avoid spoilers I'll just say it's the bit involving big green tentacles. The fact that there are tentacles is not particularly crucial to the plot. Other kinds of appendages would have sufficed, dramatically speaking, so revealing the presence of tentacles is not strictly speaking a spoiler. Likewise their dimensions and hue are not the subject of conjecture or suspense elsewhere in the story. There are tentacles in the story; they are big and green; knowing these things in advance of watching the story will not diminish your enjoyment. Conversely, nor should their presence be your sole reason for deciding the watch this story. If big green tentacles are your thing, I feel obliged to warn you that you may be disappointed.

Now I can quite see how a director or producer, on arriving at the location and getting their first good look at said tentacles, might conclude "Look, there's only one thing for it. Jon, you're going to have to play this for laughs." I am not at all unsympathetic to that view; I just think it's wrong. As evidence, I present a very similar scene used as a cliffhanger in Genesis of the Daleks, where Tom Baker's Doctor is being strangled by a few small, gaily-coloured bits of wet plastic which are so deadly that Baker is having to hold them to his own throat to stop them falling to the ground with a plop. But because Baker treats the situation totally seriously (I know! Tom Baker! It was still his first year.) it works. If you edit tightly, cutting around the naff monster as much as possible, and focus on the actor's performance, some proportion of the audience - maybe most - will suspend their disbelief. I maintain the tentacles could have worked, or at least not failed so badly, if presented sparingly. Not just flopping about all over the place.

As I say, the acting throughout is exceptional, possibly because the extraordinary conditions made for more spontaneous (i.e. not rehearsed-to-death) performances. Nevertheless, consumate professional Nicholas Courtney seems able to memorise every word of a script by smell alone, and his unflappability in the face of other artists' improvisations by necessity, inspiration, or whimsy has been the subject of many an amusing anecdote. Pertwee is clearly departing from the script for all of the above reasons at one time or another, and watching Caroline Johns react while Courtney doesn't is delicious. They're such a great trio. The closest thing we get to a villian, Hugh Burden is memorably inhuman as Channing, and if only we'd had John Breslin's Captain Munro for the next five years instead of Captain Yates! It's amazing how many members of the supporting cast don't merit a Wikipedia page, as there's not a dud among them.

This was the third script Robert Holmes wrote for Doctor Who. I would say that it was his first proper Doctor Who script. He had by now got a handle on the series and would write a few more for Pertwee, all of which we'll cover here. This story alone is enough to earn him a place in television history. Manequins breaking through shop windows is almost as vital a cultural touchstone as the moon landings, for at least some proportion of the Anglophone world. In a few years Holmes would be trailing script editor Terrance Dicks on Pertwee's last series, where his presence can certainly be felt, before taking over as script editor for Tom Baker's first three series, in which capacity I would venture to say he did probably as much uncredited writing as the rest of his substantial credited contributions before or since.

If anybody can be credited as the creator of Doctor Who, I would say it was Robert Holmes. That he started to invent the programme seven years after it had begun is I think entirely appropriate for a story about a time traveller.