Last week’s Doctor Who, if you don’t happen to know already, had an extensive scene you’d call meta: without spoiling anything, the Doctor and Belinda meet Doctor Who fans. In a way only this show can do, the show itself is fiction within itself and before this sentence gets convoluted, let me zoom to the end and just say that it was sweet. Self-aware, knowing, funny, but also warmly sweet and for me, no question, the highlight of the story.

But it’s got me thinking about how dangerous that is. I know that it’s very hard to get anyone into your story, any reader or any viewer, and once you’ve got them, I know it’s extremely easy to lose them again. Stopping a story, or seeming to stop it, in order to draw attention to how this is a TV show seems so risky that I doubt I’d ever do it if I were in that position.

And yet when it works, I think it can even draw audiences in more. It becomes a shared thing, the show and you the viewer, knowing this thing together, acknowledging what we both already know but put aside for the suspension of disbelief and the enjoyment of being carried away by the story. There’s also an element of time: even saying all of this to you now and so telling you that there was this moment in Doctor Who, that takes away something if you haven’t already seen it.

I think the clearest example of this is Newhart, the second sitcom starring comedian Bob Newhart. I get this one intellectually, I understand what the show did and I think I can feel some of why it worked, but I definitely don’t and now cannot ever get the punch that the show’s last punchline gave to its audience watching on its first transmission. Or apparently to the studio audience during the taping.

Follow. The clip is on YouTube so you can see it right now, but it’s meaningless. You need to at least know that there was an extremely successful sitcom called The Bob Newhart Show, and that later there was an at least very successful sitcom called Newhart. There was no connection between the two other than its star. No other characters were the same, no setting, no stories. And Bob Newhart played a different character. In the first show, he’s psychiatrist Dr Robert Hartley, and in the second he’s a self-help book author, Dick Loudon.

Fine. But come the 184th episode…

At the very ending of the whole eight seasons of Newhart, the studio has been set up to hide the last set, a bedroom. And the moment that set is revealed, before you even see the characters in the bed, you can hear a gasp from the studio audience because this is the bedroom from the first show, Newhart. They recognised the set.

And then you get to see the characters, of which one is played by Suzanne Pleshette — reprising her role from the first series, The Bob Newhart Show. The story claims that the entire run of this Newhart series was a dream by Dr Robert Hartley. And in the space of a few lines, Hartley manages to mock some of the recurring criticisms of the Newhart show, pointing out the absurdity of some running gags, and getting a few last laughs in.

As I say, you can see the last scene here on YouTube. I don’t know where you can catch the full 325 previous episodes of the two shows in order to fully get the gags, but.

If you’re going to do something, you do it: an apologetic dream sequence wouldn’t have worked, a half-hearted one-liner gag would’ve been rubbish. But still, Bob Newhart himself says how nervous they all were that the idea was right or not — and, nicely, properly credits whose idea it was. And then Suzanne Pleshette has said the same thing, plus how she skipped out of the wrap party afterwards because it was a wrap for their show, not hers.

But compare that to the last episode of Star Trek: Enterprise. That show had gone off the rails, if you ask me, and there as a self-awareness that just told it that only Trek fans were still watching. So it became a kind of fan-service series, and when it was cancelled early, I think it was a shame but I’d long stopped watching.

It was more than the end of one series, though. It must’ve been cancelled in 2005, which means there was an unbroken run of Star Trek shows from The Next Generation in 1987. An unbroken run, with overlaps, of four different series set in the same universe, for 18 years. The last episode of Enterprise is treated as the last episode of all of them, and it’s really written as an edition of Star Trek: The Next Generation.

I think that just as with Newhart, you needed to know the Next Generation to understand the Enterprise episode, but I also think it didn’t work. Instead of capping a long run, it seemed to negate Enterprise. It relegated the Enterprise cast to guest characters.

Maybe that’s because the whole last episode was done like this instead of being a final moment’s capstone like Newhart. Maybe, though, it’s just the old thing that the Newhart one was better written.

Maybe it’s the old thing that you can write anything, so long as you do it brilliantly.