‘He’s not got much work on at the moment, we know that. So he might be quite grateful. But perhaps you’re not convinced he’s that much of a threat?’

She had done her homework. Charles smiled. ‘I guess I’m not, not as much as you. I was more reassured than alarmed when I chatted to him. He seemed more the evangelising convert than a would-be terrorist trying to conceal what he’s up to. As for the knives – well, every kitchen has an array of lethal weaponry and as a carpenter he must already have sharp tools, Stanley knives and that sort of thing. Maybe he bought more knives because they needed them.’

‘But it worried his wife.’

‘Yes, that I can’t explain away.’ He shrugged. ‘Well, you’re the experts, you’re seeing these things all the time. I’ll have a word with Sarah and see if we can sort out some convincing household improvements. There’s no great time pressure, is there?’

She looked relieved. ‘Thank you, sir, that’s very helpful. As for time pressure, although we’ve no indication of attack planning there are some indicators reflecting a pattern that in other cases have led to attack planning. We don’t want to risk something happening and then have to admit that we had our suspicions all along but didn’t do anything because it wasn’t high-priority, as has happened before.’

Sarah was not happy about it when he rang her later. ‘I understand their arguments but I find it very hard to believe that Daniel is planning to cut our throats, don’t you? Or anybody’s. He just doesn’t seem that aggressive about it. And I feel really awkward about luring him out in order for his house to be burgled. I feel guilty enough about reporting on him anyway, as you know. God forbid that Deborah ever finds out.’

‘Searched, not burgled. But there is some joinery work we genuinely need doing, isn’t there? That back door?’

‘And those bookshelves you’ve been threatening to put up ever since we moved in.’

‘Of course, yes.’ He remembered them about once a month. ‘I could get him round to have a look at both jobs.’

‘Obviously, it would be nice to have them done. But I’d rather you did it. I suppose this sort of little deceit is all part of a day’s work for you. Not that I’m criticising.’