She decided there was no need to await Patrick’s return before resuming her search. There was no answer at the file’s addresses for Farooq Siddiqi and Shayan al-Rehman. One of the houses appeared to have been empty for a while.

Next was back to 24 Pond Street, the 2006 address of Sami’s friend, Asif Hassan. Sara heard a shuffling and sensed an eye peering through the spy hole. Then a retreat, followed by heavier footsteps. A burly man around sixty looked down on her suspiciously. Right colour, right age to be Asif’s father. Sara explained the Inquiry and her role; there seemed no further justification for subterfuge.

‘We can’t help you,’ he said in a strong Lancastrian accent.

‘I was hoping to contact a gentleman called Asif Hassan,’ she said. ‘I heard he was working as a chef in Birmingham.’

‘Who said that?’

Sara kicked herself. Careless – she hadn’t prepared for that question. ‘I can’t remember to be honest,’ she said feebly, ‘must have picked it up somewhere.’

He took a step nearer. ‘All right, kid. Now hear this. He’s not been seen nor heard of this thirteen year now. Since the morning he disappeared. With time, wounds heal. There’s no giving false hope to his mother and sisters. So leave it. Understand?’

Sara saw the grief etched in the lines mapping his face. ‘Yes, Mr Hassan, I understand.’

‘And don’t make that assumption neither.’ With that, he closed the door. Sara kicked herself. Why hadn’t she asked Sami the source of the rumour? How could he have heard something about Asif that was so clearly unknown to his family?

The final chance was 113 Medlar Street, home at one time of Iqbal Jamal Wahab. His files suggested that, after returning home, probably from Syria or Iraq, he had disappeared again. If he was known to have died in conflict, the British government or jihadists themselves would have told his parents. If he hadn’t, where was he now?

This time the door opened – accompanied by an unfriendly reception from a young man she assumed to be his brother. Overhearing the doorstep conversation, an older man stepped in. Sara explained as before her role and its confidential nature.

‘Yes, I’m Iqbal’s dad and it sounds good what you’re doing, love, but we can’t help you.’ His tone was polite but firm.

‘I realise he’s not here any longer,’ she said, ‘but could you just tell me when you last saw him?’

‘As I said, we’d rather not and I’d ask you to leave us in peace. He came home briefly but we haven’t seen or heard of him for four years now. We’ve not given up but we’d best not get involved.’