The police technicians would be able to track down the site host and administrators. With any luck, the cyber-crime unit might already have data on LfA. ‘Did the posts say what the purpose was of today’s flash mob?’

He’d said no but I wasn’t convinced.

‘He says they didn’t care,’ said Rima. ‘But from how he describes it, it sounds like it was something to do with anti-gentrification.’

‘Yes. Genti-thingy.’ He pointed at the street and lapsed back into Arabic.

‘Was any incentive offered to turn up?’

‘He doesn’t want to get anyone into trouble. They were told not to tell anyone.’

‘Tell anyone what?’ I looked from Rima to Ali.

Ali was silent.

‘Who told them not to say anything?’

‘Frazer.’ Rima emphasised the name and raised her eyebrows. I got the impression she was trying to check I’d taken note.

‘What was the payment?’ Please, God, may it not have been drugs.

‘Sometimes he gave them a bit of money or some food,’ said Rima. ‘And masks.’

‘What sort of masks?’

Ali and Rima talked in Arabic. ‘Black bandanas with the LfA logo on them,’ she said.

This was news. ‘And drugs?’

‘NO.’ Ali was on his feet now. His eyes were flashing with fear, and for a moment I wondered if he was about to make a dash, but his body swayed and rocked. He put his hand out and sunk back down onto his seat. ‘Not drug.’

‘OK.’ I changed tack. ‘Today – who brought the speakers?’

‘He says they were there when they arrived.’

‘They?’

‘He came with his brother and his brother’s girlfriend.’

‘What are their names?’

‘Riad.’

‘How old’s he?’

‘Nearly sixteen.’

‘And Sophie,’ Rima said. ‘She’s doing A-levels at New City College.’

‘Does Riad live with you in York Square?’

‘Yes.’

‘What number in York Square?’

‘Twenty-eight. Opposite the entrance to the park.’

‘Where are Riad and Sophie now?’

Fear filled Ali’s eyes and he covered his mouth with his hand.

‘He doesn’t know. They got separated . . . When the fire started . . . they ran for cover and . . . Riad’s not answering his phone. He says he’s scared.’

‘Which direction did they run in?’

‘That way and left.’ He pointed.

‘That way?’ I gestured. ‘That’s right.’

‘Ach.’ He punched his leg, as though he felt stupid. He turned to Rima and spoke to her.

‘Down there and right,’ she said. ‘He says his brother will turn up. He’s probably dropped his phone or they’ve gone to get some chips.’

‘Ali. Are you sure neither of them entered the building before it went on fire?’

‘They were both with him.’

‘We’ll need their descriptions . . . and a formal statement, Rima, if you can translate, please? Ali, if you hear from your brother or Sophie, please inform us straightaway.’ I summoned a uniformed officer and began briefing him.

Dan, 3.45 p.m.

Dan, 3.45 p.m.