‘There’s a sort of flicker for a moment,’ said Johnny. ‘Then … zap. Er … what’ll happen if he comes out where there’s a fridge or something? Is that as bad as a concrete wall?’

‘I don’t know much about fridge atoms,’ said Yo-less. ‘They might not be as bad as concrete atoms. But I shouldn’t think anyone around here would need new wallpaper ever again.’

‘Wow! An atomic Wobbler!’ said Bigmac.

‘Let’s get the trolley and go after him,’ said Johnny.

‘We don’t need it. Leave it here,’ said Kirsty.

‘No. It’s Mrs Tachyon’s.’

‘There’s just one thing I don’t understand,’ said Yo-less, as they hauled the trolley across the field.

‘There’s millions of things I don’t understand,’ said Johnny.

‘What? What? What are you going on about now?’

‘Televisions. Algebra. How skinless sausages hold together. Chinese,’ said Johnny. ‘I don’t understand any of them.

‘The trolley’s got no works,’ said Yo-less. ‘There’s no time machinery.’

‘Maybe the time is in the bags,’ said Johnny.

‘Oh, right! Bags of time? You can’t just shove time in a bag!’

‘Maybe Mrs Tachyon didn’t know that. She’s always picking up odds and ends of stuff.’

‘You can’t pick up time, actually. Time’s what you pick things up in,’ said Kirsty.

‘My granny saves string,’ said Bigmac, in the manner of someone who wants to make a contribution.

‘Really? Well, you can’t pick up the odd half-hour and knot it on to another ten minutes you’ve got spare, in case you haven’t noticed,’ said Kirsty. ‘Honestly, don’t they teach you any physics at your school? Fridge atoms was bad enough! What on earth’s a fridge atom?’

‘The smallest possible particle of fridge,’ said Yo-less.

Perhaps you could save time, Johnny thought rebelliously. You could waste it, it could run through your fingers and you could put a stitch in it. Of course, perhaps that was only a manner of speaking and it all depended on how you looked at it, but Mrs Tachyon looked at things in a corkscrew kind of way.

He remembered touching a bag. Had time leaked out? Something had hissed through his fingers.

‘You can’t have the smallest possible particle of fridge! It’d just be iron atoms and so on!’

‘A fridge molecule, then. One atom of everything you need to make a fridge,’ said Yo-less.

‘You couldn’t ha— well, all right, you could have one atom of everything you need to make a fridge but that wouldn’t make it a fridge molecule because—’ She rolled her eyes. ‘What am I saying? You’ve got me thinking like that now!’

The rest of the universe said that time wasn’t an object, it was just Nature’s way of preventing everything from happening at once, and Mrs Tachyon had said: that’s what you think …

The path across the field led through the allotments. They looked like allotments everywhere, with the occasional old man who looked exactly like the old men who worked on allotments. They wore the special old man’s allotment trousers.