It’s interesting watching this episode to see the evolution of Doctor Who’s approach to time travel. In John Lucarotti’s next script, he’ll introduce the idea that ‘You can’t change history, not one line.’ That’s often held to be the standard for Season One. But between the TARDIS crew showing the secret of fire (and humanity) to the Tribe of Gum, and the Doctor’s readiness, in this episode, to whisk away Marco and his retinue in the TARDIS to escape a bandit attack, I’m guessing the ‘not one line’ rule hadn’t been invented yet. That’s probably because the whole idea of changing history hasn’t really been touched on: for all that they’re prisoners and subjected to repeated conspiracies by Tegana, the TARDIS crew still seem to be treating this adventure as a mildly diverting holiday, and their need to escape never seems especially desperate.

Rider from Shang-Tu is another holding episode that doesn’t particularly change the status quo from last week. Tegana is still plotting, unsuccessfully, with bandits. Marco is still insisting the TARDIS will be gifted to the Khan. Other than a short, relatively exciting sequence right at the top, where Ian displays an unexpected knowledge of the explosive properties of bamboo, this is quite a talky episode. Luckily, the script is quite witty. Hartnell gets several great one-liners – ‘Thanks for nothing,’ when Marco says the crew are his prisoners, not the Khan’s, and ‘What does he think it is? A potting shed?’ when the TARDIS is moved to the stables.

It also benefits from some lovely scenes between Ian and Marco, where the two men candidly discuss Ian’s desire to escape. This forms the nub of the episode. ‘Marco, I wish I could explain to you how important the TARDIS is to us,’ says Ian. ‘And I wish I could explain to you, Ian, how important it is to me.’ Marco replies. To both of them, the TARDIS represents freedom, and the chance to get home. To Susan, too: later in the episode. Ping-Cho reminds us what’s at stake when she asks Susan, ‘If Messer Marco does give your caravan to Kublai Khan, you will never see your home again?’ Meanwhile, to Tegana it represents power and the chance for personal glory: an object that can be a warlord’s tomb, or his throne.

But, for all the nice dialogue, nothing especially interesting happens for most of the episode. There’s another quasi-educational interlude when Ling-Tau explains how he has ridden 300 miles in a day. Ping-Cho and Susan chat about fish. Marco fills in his journal. Tegana glowers. Whereas by its fifth episode the Dalek adventure was kicking off the second part of the story with the promise of a dangerous expedition, monsters in a lake, and Daleks planning another nuclear explosion, this one is content to have a very gentle week of pottering about.

The cliffhanger, with the time travellers finally regaining access to the TARDIS, does raise the stakes. But it’s immediately undermined because Susan has wandered off, stupidly, and bumped into Tegana. For all the pretty sets and script, this episode is just treading water.

Rider from Shang-Tu no longer exists. Not in any of its regenerations. This review is courtesy of the excellent Loose Cannon reconstruction

Next episode: Mighty Kublai Khan