‘By not thinking about it,’ Casey said. Then she saw Hessa’s face, and dropped the flippancy. ‘You have to make your own rules, Hessa. And make sure they make sense for you. That you can live with them.’

Speaking to Hessa, Casey had remembered Miranda’s words, years earlier: ‘Remember who your friends are. You’ve got a billion possible sources, and a finite number of friends. Never screw over a friend.’

‘Anything else?’ Hessa had looked hopeful.

‘Decide what you’re happy with, and don’t break your rules,’ said Casey. ‘And if someone is a source, you never, ever throw them under the bus. Never.’

‘But isn’t that so artificial? Just giving us an excuse to keep secrets.’

‘I suppose so.’ Casey pondered it. ‘Like barristers insisting on the cab-rank rule, so that they can nod and shrug to each other, “You know how it goes. Everyone needs representation.” But there has to be something. Some truth.’

‘But we lie’ – Hessa hesitated on the word – ‘all the time.’

‘I know,’ said Casey. ‘But that is why it matters. If I give my word to a source, I don’t break it.’

‘Never?’

‘Never.’

She didn’t tell Hessa the indescribable truth: it will be hard. It will be hard, and it will change you, for ever.

Casey looked up at Miranda now. ‘Hessa’s fine,’ she said.

‘Good.’ Miranda gave her a long look.

‘I’ll go to Emily,’ Casey said. ‘I’ll talk to her, just the two of us.’

‘In Surrey? Are you sure? You hate Surrey.’

‘Yes.’

It was in the car, driving back to London, that Casey spoke.

‘You’re being too hard on them,’ she said.

‘Given what they’ve done?’

‘You know,’ Casey said carefully, ‘that it’s irrelevant right now.’

Miranda was silent, watching the columns of cars on the other side of the road. Headlights, blurring in the rain. She knew it was irrelevant. Facts, not opinion: all that mattered. Usually, it was Casey who struggled.

‘All right.’ Miranda forced down the anger.

‘Is everything OK?’ Casey’s voice was expressionless.

I am going to work on my marriage. As if it were a tapestry, for some lofty medieval altar.

I’m going to save my marriage . . .

‘I don’t know.’

‘I’m sorry. But that’s not their fault.’

‘I know. I know.’

The car fell into silence. Miranda stared out of the window, clenching her jaw, and abruptly felt her throat close up, the memories overpowering as cheap perfume.

He’d caught her one Sunday morning. Not one Sunday morning: the Sunday morning her father died. Crying in that grand old court, in the dawn, the blossom still wet from the dew, as everyone quietly slept.

Are you OK?

I’ve got to . . . I’ve got to get the train . . . My father . . . I don’t know . . .

I’ll help.

He helped her pack. Then the trains were chaos. Sunday: of course.

I’ll drive you.