Doctor Who‘s sixtieth anniversary extravaganza from Big Finish continues with Time Lord Immemorial, the sixth instalment in the eight-part Once and Future saga. Like Lisa McMullin‘s previous story, this is a bit of a runaround, but it has some good ideas and character interactions at its heart, which means it’s well worth a listen.

The most anticipated part of this release has got to be the meeting of Christopher Eccleston‘s Ninth Doctor and the late David Warner‘s Unbound Doctor. Weirdly, though, the moment is quite underplayed, both Doctors acknowledging the existence of the other and then just kind of moving on. Their interactions throughout are, to be honest, underwhelming, though it’s lovely to finally hear Warner interacting with another Doctor, even if the moment is tinged with sadness knowing this will be his final performance in the role.

Much more interesting is the meeting between the Ninth Doctor and the Lumiat (Gina McKee), the Master’s only truly good incarnation. Having the Ninth Doctor meet the Master would ordinarily be impossible, so this is a fun way to get the two characters together without messing up the Doctor Who mythos. Eccleston and McKee strike up an engaging rapport, no surprise given their history working together, and there are some good scenes between them as they contemplate their aeons-long relationship with one another.

Also starring here is Nicola Walker, reprising her role as Liv Chenka and, while her performance is as impeccable as always, her character feels a little disposable here, not really having a lot to do. We’ve already heard Liv meet the Ninth Doctor, so it’s a bit baffling why the story team chose to have her not recognise him or follow up on their previous encounter here. Although I adore Walker and her character, I couldn’t help thinking Lisa Bowerman‘s Bernice Summerfield would have been a better fit here, not only because she’s already travelling with the Unbound Doctor and doesn’t require narrative loopholes to appear like Liv does, but because her archaeological background really fits with the setting of the story.

Overall, this is an entertaining story in terms of character interactions, but the plot is a little nebulous and doesn’t really advance the overall storyline like the previous episode did. Solid, but unremarkable.

The Martian Invasion of Planetoid 50 is available on CD or download from http://www.bigfinish.com