‘She had a difficult time with Peter – placenta praevia. He was early, she lost a lot of blood. It was Josh who was most afraid of going through that again – losing her.’

Another little note in Patel’s book.

‘Did she talk to you about their relationship?’

‘Never negatively. Unless you count joking about how they never had enough sex – too bloody tired after work, being parents, the house, what’s for dinner, you know.’ Maybe they didn’t; Baby Cop was too young and Thomas didn’t look like she’d settle for less than perfection in any area of her life. ‘But it was nothing, just idle talk over a bottle of wine, nothing to do with how much she loved him, which was a lot. They’d been together since she was sixteen.’

‘You never had reason to believe she felt frightened of him?’

‘No.’

‘Did he try to control her at all – dominate her? Did you ever see him behave in a way you’d describe as intimidating?’

The image appeared in her head without warning; she shoved it away.

‘No,’ she said. ‘Generous, protective, kind, yes; controlling, dominating, no.’

‘DI Nuttall contacted Maggie Hammond because he knows she sometimes works with local women experiencing domestic violence.’

‘Maggie knew Corinna but only through me. She wouldn’t have anything different to tell you about Josh. She’d have told me – today if not before.’

‘And what about Corinna herself – the other side? You never had reason to think she might have been bored of the marriage? That there was someone else? They’d been married for …’ Patel flicked back a couple of pages in his notebook, ‘twelve years.’

‘No, she never even hinted at that.’

‘And she would?’

‘Yes.’

‘If she’d met someone else or was thinking of leaving him – for whatever reason – might that be enough to make him lose control? If he loved her as much as you say.’

‘Didn’t happen.’

‘Infidelity can make people react in extreme ways,’ pronounced Patel as if he was whipping back the cloth on a remarkable truth. ‘Not just men, either. Totally normal people can go completely off the deep end and behave in a way no one could predict. It could also explain why Josh would set the fire knowing his son was upstairs – these kinds of killings can be a misguided attempt to keep a family together, in death if not in life.’

‘I’m aware.’

DS Thomas sat back and crossed her legs as if to signal that she was satisfied, the heat was now off. Robin braced herself.

‘You were in the job yourself, weren’t you?’ Thomas said. ‘The Met.’

Here it came.

‘DCI with HMCC.’

‘That’s …?’ Patel, pen poised.

‘Homicide and Major Crime Command. I led a murder investigation team.’ Fifty people.

‘Until quite recently.’ An eyebrow rose towards the Emeli Sandé quiff.

‘Just after Christmas.’

‘You left because …?’