Empress Of Mars (S10E09) is comfort zone Doctor Who at its finest.

After the promised-much-more-than-it-delivered epic storytelling of the past three weeks, “Doctor Who” comes back down to Earth (well, one planet out) with “Empress Of Mars”, landing firmly in the series’ comfort zone.

Visiting NASA on a whim, the Doctor, Bill and Nardole are present to witness the discovery of a message written on the red planet’s surface under the ice caps: ‘God Save The Queen’. The TARDIS team travel back in time to Mars in 1881 and are surprised to find a troop of Victorian English soldiers living on the planet with an Ice Warrior acting as their valet.

There’s always been a vein of nostalgia running through the Capaldi era and in “Empress Of Mars”, writer Mark Gatiss (now the revived series’ longest-serving writer) has delivered a sincere and shameless love letter to the Third Doctor’s era. It’s one of those quintessentially Whovian stories that you could literally replace the Doctor and companions with any of his incarnations and the story would still work well but there’s a distinctly Pertwee flavour to the whole affair, apparent long before the delightful cameo at the end. The nostalgia isn’t just confined to the classic series either, as the current one gets a nod or two as well, especially in the portrait of Queen Victoria showing Pauline Collins from season two’s “Tooth & Claw”.

The amusing conceit of Victorian soldiers on Mars is explained in a credible way and, like the classic serials of old, the troops are given distinct personalities and even some modest character development. The Ice Warriors continue their more modern development as Doctor Who’s answer to Star Trek’s Klingons, bound as they are by the ways of honour and battle but they’re effective monsters and the interplay between their warrior ways and the true nature of courage gives the episode a nice emotional edge to it.

The production design is lovely, from the traditional tunnels and caves of Who to the Victorian-era ‘spacesuits’ it’s in the little details the episode’s quality shows. The Empress herself is a fine creation, adding some more depth to the Ice Warrior lore and the emergence of the reviving warriors from the cavern walls harkens back to the Cyber-reveal of “Earthshock”.

Ironically, the few things which didn’t work in the episode all link to the overarching mystery of the season. There’s no satisfactory explanation (yet) for the TARDIS’ abrupt and apparently arbitrary dematerialisation once the Doctor and Bill are on Mars. Its eventual return, piloted by Missy, sees her ask the Doctor earnestly and repeatedly if he is alright, suggesting I’m not the only one who thought Capaldi’s accent got a little weird at times throughout the episode. Are we in for some Freaky Friday hijinks where it turns out Missy and The Doctor swapped bodies at some point? That would be fun. Finally, it can’t be just me who thought it was a dick move by Bill to completely spoil the movie “The Thing” for the vast Doctor Who audience who are too young to have seen it yet.

“Empress Of Mars” is a solid episode of “Doctor Who” in the classic style, it’s lack of mould-breaking ambition both its strength and its weakness. It’s entertaining enough but in amongst this season it feels a little under-par and might have been better placed earlier on in the run than now, in the pause for breath between the mid-season trilogy and the season’s closing moments. Still, it deserves to be bumped up a point just for the sheer joy of Alpha Centauri’s cameo at the very end, especially as 92-year-old Ysanne Churchman came out of a 25-year retirement to voice the character once again.