They stopped outside a general store, looked at each other and laughed. Then they entered the shop. Hobbes stood in a bus shelter for fifteen minutes or so until they emerged again, carrying plastic bags, two each, loaded with produce. The squat’s weekly shop, probably. They moved on to busy Rye Lane, where they bought things from market stalls and other shops. Hobbes kept his distance. And then they walked back along the street directly towards him. Now was his chance: he could step in front of them and get them talking. He could play it cool and ask misleading questions and gather whatever information he could from them, without them knowing; he could make certain that Martin was actually living at Cromwell House. Or he could take out his warrant card and play it tough, make up some misdemeanour to threaten them with. He might even give in to his feelings and plead with them to show him where his son was.

Instead he let them walk on towards the squat.

He remembered the advice he’d given to Glenda, to let Martin have a few days to make up his mind. Yes, that was the best thing to do, the best thing …

He set off towards his car, along the edge of a small park.

‘Why are you following us?’

Hobbes turned and saw the girl staring at him from the line of grey trees. She was late teens, with straggly unwashed hair, ashen face, a little make-up. Her jacket was held closed with the strap of an army-surplus shoulder bag. A lapel badge showed her support for the Anti-Nazi League. She didn’t move, or say anything further, just stood there looking at him, the two heavily laden shopping bags hanging from her hands. A car passed, then a woman pushing a pram.

When the squealing baby was out of earshot Hobbes said, ‘I’m not from the landlord.’

The girl didn’t respond.

‘I’m a police officer. If there’s anything you need help with …’

‘All we want is to be left alone.’

‘And boarding up every window and door helps with that?’

‘We have to. If it’s not the council, or the bailiffs, it’s the cops. And if it’s not them, it’s the skins.’

‘Skinheads?’

She nodded. ‘They like to do night raids, beat up a few hippies and punks.’

Hobbes knew this was true: the youthful tribes of London at war with each other. He thought again of his son’s welfare. ‘Still, you’ve taken it further than most,’ he said, ‘locking yourself away in there.’

‘What’s it to you?’

The girl didn’t wait for an answer. She set off, moving away from the trees, back on to the pavement.

He stopped her and asked, ‘What’s your name?’

‘Get your hands off me!’

‘You can make a name up, I don’t care. I just need to talk to you.’

‘I don’t talk.’

One shopping bag fell to the ground, then the other.

‘So why did you wait?’

‘To tell you to fuck off.’