‘Those smells featured, I think.’

Birley shook his head. ‘Then Sandra wouldn’t have gone in it. She might have pressed the button and opened the doors. But if the lift smelled as bad inside as you say it did, she wouldn’t have used it. No way. She couldn’t stand bad smells in an enclosed space. It made her feel sick.’

‘So you think she’d have used the stairs, even though the lift was working?’

‘Yes, I’m sure she would. You can count on it.’

Trish put her hand on her brother’s shoulder, perhaps detecting some sign of emotion that Fry had missed. She left it there for a few moments, while Birley breathed a little more deeply. The two detectives waited. Fry noticed that Trish’s arms were broad and fleshy, yet ended in surprisingly small, elegant hands with long fingers, as though the hands had been transplanted from someone else.

‘I’m fine, really,’ said Birley at last.

‘Your wife was late leaving the office too, wasn’t she, sir?’ said Fry.

‘Yes, she was. There was a late meeting, and then she had some work she had to finish. She’s done very well for herself at Peak Mutual, you know. She’s an account executive.’

‘Did you know she’d be late?’

‘She rang me just before five thirty to let me know, and told me not to wait for her to get home before I had something to eat. I got a pizza out of the freezer and left half of it for her. Hawaiian-style. She likes pineapple.’

Fry saw Trish’s hand tighten on his shoulder in an affectionate squeeze. She was anticipating Birley’s realization that the five-thirty phone call was the last time he would ever speak to his wife, that Sandra would never come home to eat her half of the pizza. But the moment didn’t come. Or at least, it didn’t show on Geoff Birley’s face.

‘When Mrs Birley called, you were already home, sir?’ asked Hitchens.

‘Yes, I was on an early shift.’

‘Your wife didn’t happen to say what the work was she had to finish?’

‘No, she didn’t often talk about her work. She told me about the people in her office – little bits of gossip, you know. But she didn’t bring her work home. She was good at her job, but she liked to keep the two halves of her life completely separate, she said.’

It was a good trick if you could do it. Fry glanced at Hitchens, who nodded.

‘Mr Birley, we have to ask you this,’ she said. ‘Can you think of anyone who might want to harm your wife?’

He frowned and shook his head. ‘No, not at all. Everybody liked her. She wasn’t the sort of person to get into arguments. She hated upsetting people. If there was someone at work she didn’t get on with, she would just try to avoid them.’

‘I see.’

‘It wasn’t somebody Sandra knew, was it? Surely it was one of these lunatics who prey on women? She was a random victim. She was in the wrong place at the wrong time.’