I love it when the title of something makes it into dialogue (best of all is ‘I must have scared THE LIVING DAYLIGHTS out of her’). Here, it turns out that ‘the Armageddon factor’ is mutually-assured destruction, and there’s a sort of vague theme that the nuclear war between Atrios and Zeos is a reflection of the cosmic Armageddon factor between the Black and White Guardians. Certainly, this episode focuses more on that conflict and the power of the Key of Time than any since The Ribos Operation – Part One.

The scenes of the Doctor and Romana postponing doomsday by jury-rigging the completed Key are brilliant: lightly touching on weighty themes of assumed godhood and absolute power. Romana seems both appalled and a bit turned on by being ‘gods for an hour or two’, musing that ‘all power corrupts’ while egging the Doctor on to ‘command it’ with a seductive glance. These are hardly the most groundbreaking concepts, but they at least imply something more important at stake than who has some plastic segments, and go a long way to giving greater significance to the battle between light and darkness apparently raging across eternity.

Again, this is a very uneven script suggesting that it’s been partly rewritten (possibly by Douglas Adams). The faked sixth segment is a brilliant idea, and its decaying time-loop effect is very effectively conveyed via the countdown in Mentalis’ control room. The controlled Princess Astra is reasonably effective too. But then there are interminable scenes of Mentalis being dismantled, the Marshal’s missiles lowering into position, Merak falling into a pit (? it’s very unclear), and Dayvd Harries doing a comedy pratfall when he gets shot in possibly the unfunniest moment in all of Doctor Who. But this ends well, with everyone lured to the Shadow’s planet (shame it’s a fairly dull model) and a sense of events coming to a head.

Next episode: The Armageddon Factor – Part Five