She doesn’t apologise for keeping them waiting. She’s wearing a plain sleeveless navy dress that makes her look a million dollars, her platinum hair caught up in a neat bun at the nape of her neck.

DCI Hollander stands and introduces himself and his colleague. ‘It’s good of you to take the time to talk to us,’ he adds.

‘What do you need to know?’ Millie asks.

‘When did you last see Felix Porter?’ DCI Hollander says, matching my wife’s brisk tone.

‘Seventeen days ago,’ Millie says precisely. She smooths her skirt neatly beneath her thighs as she sits down. ‘I went round to the Glass House to talk to him. We had a row. I haven’t seen or spoken to him since.’

‘The Glass House?’ DCI Hollander repeats.

‘It’s what people round here call the Porters’ house,’ I explain. ‘It’s a bit of a local landmark.’

‘You had a row?’ DS Mehdi says. ‘What about?’

He’s the one I’m worried about. My wife is a smart woman, but she’s no match for modern forensics. If she’s … done something, if she’s made Felix disappear, they’ll find out no matter how careful she thinks she’s been.

‘I wanted him to sell the house to me,’ Millie says. ‘Stacey wanted a divorce. He was being unreasonable. We argued about it.’

Millie’s simply telling the truth as she sees it. She doesn’t realise how cold, how clinical, she sounds.

My eyes follow DS Mehdi as he wanders out into the hall. Is he looking for something specific, or is he just waiting to see if something – some clue – presents itself? I’m torn between following him and staying here to protect Millie.

‘It wasn’t the first time you’d argued, was it?’ DCI Hollander asks Millie.

‘I’m guessing you already know the answer to that, or you wouldn’t be here,’ Millie says.

DCI Hollander acknowledges the point with a slight nod. ‘You didn’t have a good relationship,’ he confirms. ‘We have it on record that you had several heated arguments with Mr Porter.’

‘He was an unpleasant man,’ Millie says evenly.

‘How so?’

‘He was physically abusing Stacey. I saw the bruises on her arms. She even came round to our house with a black eye a few weeks ago. It’s why she finally left him.’ She indicates me. ‘Tom was here. He can tell you.’

With every word Millie is giving the detectives motive for murder. They probably think my wife and Stacey Porter are in it together.

‘Mrs Downton,’ DCI Hollander asks, ‘when you saw Mr Porter that Sunday did he mention anything to you about going away?’

‘No, though I certainly recommended it.’

‘How did he seem when you left him?’ DCI Hollander asks.

Millie looks amused. ‘Alive, if that’s what you mean.’