Emerging into the back garden, he was just in time to see a plump rump disappear over the back wall.

Cursing horribly, he opened his com and shouted, ‘He’s getting away. Over the back wall. Where are you?’

‘I can see him,’ said Farrell. ‘There’s an alleyway. He’s not very fast. We’ll get him easily. Lockland?’

‘I’m just . . .’ Lockland appeared at the other end of the alleyway. ‘We’ve got him trapped between us.’

‘On my way,’ said Parrish and sprinted for the back wall himself, confident that the Plimpton family – if that was who they were, because he suddenly realised he hadn’t checked – would be too elderly, too young, too unfit, too fat, or too stupid to follow him. Heaving himself over the wall, he dropped heavily on to two large black plastic containers which appeared to have been placed there for the sole purpose of interfering with the Time Police in the execution of their duties, had anyone in the late 20th century actually been intelligent enough to think of such a thing.

He hit the bins with a crash, bounced and hit the ground with another crash. Both bins tipped over with him, their lids came free and he found himself rolling among the remains of every meal the Plimptons had enjoyed over the last seven days, together with some dubious-looking material of a very personal nature.

Fighting free, he rolled over and stood up to assess the damage.

‘What the fu . . . ? What am I covered in?’

‘Household rubbish,’ panted Farrell, joining him. He pointed down the alley. ‘He went that way. Is that smell actually you?’

Parrish had lost interest. ‘Why don’t these people have household incinerators? Are they living in the Dark Ages? Why are they not all dead of plague or worse? There must be rats everywhere. I tell you, we’re all going to die of something unspeakable. None of us are likely to survive this assignment.’

There was a shout from further up the alleyway. Lockland was using the plastic bins with which the alleyway was generously endowed to climb over another wall.

Back in the pod, North and Ellis were barely able to stop laughing long enough to refill their mugs.

Farrell and Parrish pounded down the alleyway and followed Lockland over the wall, only to find themselves in an open space covered in coarse grass and with a broken goalpost at one end.

‘There,’ said Farrell, pointing at the plump figure racing away from them, albeit very slowly. Lockland was not far behind. A handful of small children, who should almost certainly have been in school and weren’t, watched them go, shouting derisive comments.