Undoubtedly the best of the three New Who spin-off series, The Sarah Jane Adventures sees the former companion pick up young companions of her own, including alien experiment and surrogate son Luke, his friend Clyde, and next door neighbours Maria and then Rani. At its best, it was as good as Who, sticking closely to the classic cliffhanger-driven format of the parent show, and it was hugely popular too. At the time that Sladen passed away, it had already been recommissioned for its fifth and sixth series.

With these plans in mind, there are a couple of story ideas that sadly weren’t realised. For instance, Davies has previously spoken about how he planned to bring back Sophie Aldred as the Seventh Doctor’s companion Ace in the sixth series, along with another repeat appearance for Katy Manning as Jo Grant. There’s not a Who fan alive who couldn’t have got on board with that.

Luke left Bannerman Road to go to university in the first story of the abbreviated final run, but Clyde and Rani are popular characters who just disappeared with the series. For a while, fans speculated that they might show up in Doctor Who during Matt Smith’s era, but it’s hard to see how you do that without addressing what Sarah Jane is up to. Unlike the Brigadier, who was movingly sent off in The Wedding Of River Song and then referenced many times in Moffat’s scripts thereafter, it’s only right that her story is left open.

There’s also the question of Sky, another alien child who moved in as Luke was moving out. She’s dropped off in the first story by the Shopkeeper, a mysterious Doctor-like wanderer who had first appeared in Series 4’s Lost In Time. The writers intended to bring the Shopkeeper back and reveal more of his true nature in the unfilmed finale, The Battle For Bannerman Road, but it wasn’t to be. Both Davies and Neil Gaiman have suggested he was an incarnation of the Corsair, the Time Lord buccaneer mentioned in The Doctor’s Wife.

These bits aside, writer Gareth Roberts has always said that The Sarah Jane Adventures was intended as “a full-blooded drama” and not “just a children’s show”. While more kid-friendly by design, the show was always telling emotional and ambitious stories and it was always particularly good when exploring Sarah Jane’s inner life. It’s a show that could have ran and ran, and was meant to.