As a climax to Doctor Who‘s longest serial to date, Destruction of Time is an sombre, hollow experience. The first part of the episode wraps up the Mavic Chen story – unlike earlier episodes where hetook a high-handed approach to his Dalek allies, this time the scene is full of menace, as his hubris gives way to madness, and he is exterminated – denying Sara the opportunity to execute justice for her brother and the Solar System.

In the confusion, it turns out that the Doctor has separately made it into the Dalek bunker, and plans to turn the Time Destructor against them – again relying on their over-used reluctance to shoot for fear of damaging something. The second half of the episode is the consequence of using the weapon – and it must have been an astonishing experience to see the jungles of Kembel withering and turning to dust, accompanied by the pulsing howl of the destruction of time.

The desperate flight back to the TARDIS is every bit as harrowing as Katarina’s death: Sara, ageing to death and crumbling, like a Hammer Vampire, before our eyes; the Doctor’s desperate cry of ‘Go forward!’; the Daleks screaming as they devolve into embryos; Steven’s voice breaks as he contemplates the sacrifice made to stop the Daleks – ‘Bret, Katarina… Sara…’

The Daleks’ Master Plan is vast: it’s the millstone that weighed down John Wiles, and finally broke him. It’s the success story that BBC execs were still talking about five years later, and that Barry Letts wanted to revisit for the 10th anniversary. It’s the one that was so big it wouldn’t fit into one novelisation. It’s a capstone of everything the series has done so far – Earth’s history, alien planets, the TARDIS landing on the day of broadcast, ruthless Daleks, chases through time and space. It’s got the silliest comedy episode and the most brutal horror in the space of three weeks. It’s got whispering Daleks that inspired Russell T Davies.

And it ends with everyone together in one room, a crucible, which must have been an inspiration for RTD’s own Dalek epic, Journey’s End. But it’s hard to imagine the new series doing anything quite so nihilistic. Unlike Katarina, Sara doesn’t sacrifice herself doing something meaningful, like holding up the Daleks to buy the Doctor more time. She just dies, and is left where she falls. There is no great showdown with the Supreme Dalek, no final triumphant speech or easy platitude. Like the end of King Lear, it’s just the survivors, contemplating the promised end. ‘What a waste… What a terrible waste.’

Next episode: War of God