‘I need your help to save the world. Time itself is under threat.’ This is different: the team scattered through time on their own mini-Key to Time quest. The Key, in this case, is a magic metal chronosteel but to all other intents and purposes, including being disguised as different objects and its power to re-shape destiny, it might as well be the crystal cube Tom and Mary had to put together in 1979. It even has its own version of the White Guardian, dressed like a genial shopkeeper.

It makes for a nice change in pace, as each of our heroes lands at a different point in history. Rani at the nine-day court of Queen Jane; Clyde battling Nazis in World War Two and Sarah Jane teaming up with a Victorian ghost hunter. As usual for the show, some of the less pleasant aspects of history are lightly touched on – Clyde is called a ‘negro’, and Rani is treated with suspicion as a ‘foreigner’ from ‘the court of the Taj Mahal’. Sarah Jane has the least problem slotting in, but perhaps the biggest conundrum as a Stone Tape echo of the future breaks through into the past.

Next Time: Lost in Time – Part Two