Not to mention the cunning servant Raquella, she helps Jonathan get to his dad on time.

Since he has been attacked by a werewolf, been close to being stabbed with a knife and swam in the “pool of pain”.

S. F. Said, writing for The Guardian, said "It's a marvellously convincing dystopia; the only downside is that Darkside, when we get there, seems friendlier than modern London.

Perhaps that's Becker's point: that the Victorians' grotesque nightmares are less terrifying than the everyday reality we've since created.

We never see enough of Darkside to be certain of this; but tantalising hints suggest that the shadow-city will be more deeply and fully developed in sequels.