'Thin Ice' review [Sarah Dollard]

The Doctor and Bill in their regency garb.

After trying to return to St Luke's, the Doctor and Bill land in London at the last frost fair. Little do they know that there's something lingering under the frozen Thames.

Writer Sarah Dollard previously wrote season 9's 'Face the Raven'.

Spoiler Zone

The episode

Bill's first foray into the past makes for good viewing, with a fun Classic Who-esque exploration of the setting before the plot kicks in. It doesn't matter that the main plot is basically Torchwood's 'Meat' when the Doctor and Bill are having this much fun and the world is realised so wonderfully. The exploration of the frost market reminds us that travelling in the TARDIS isn't primarily about fighting bad guys and saving people - it's about fresh experiences in new worlds, and both the Doctor and Bill relish this.

Lord Sutcliffe doesn't make a convincing or interesting villain, not making an appearance until near the end and being much too over the top evil. The gang of street urchins are sympathetic enough, with Kitty as the regency's answer to World War II's Nancy from 'The Empty Child' and 'The Doctor Dances'. The death of Spider isn't shocking just for Bill - it's rare for a child to die on Doctor Who, let alone for it not to be reversed somehow like the destruction of Gallifrey.

If 'Smile' was Bill's somewhat disappointing answer to Rose's 'The End of the World', this episode is a worthy counterpart to Rose's 'The Unquiet Dead'.

TARDIS crew and co.

• The Doctor: "It's just time travel. Don't overthink it." The Doctor is carefree and ready to explore, even dressing up like the locals in this instance.
• Bill Potts: "Every choice I make in this moment, here and now, could change the whole future." Bill is horrified after witnessing death for the first time, and truly mortified when she learns that the Doctor has killed before.
• Nardole: "As long as I'm still here, you are going nowhere." For comic-relief, Nardole really is a downer.