She looked alarmed. ‘A statement? No, I can’t … He would … You don’t understand. If James knew I was talking to you, even like this … I’ve told you what I know. If I hadn’t and you’d found her anyway, it would have looked like I’d put her there myself, but I can’t do any more than that.’

Her hand shot forward and covered his where it rested on the table; the other went to her mouth. Eyes already wide, pupils growing in fear like zoom lenses.

‘No one can know about this. About me, I mean. Go there. Find her, but you can’t use my name.’

‘It’s not that simple, Mrs Locke.’ Porter sandwiched her hand with his free one, firm but reassuring. ‘We need you. Without you we have no one identified at the scene. Without you there was no girl hauled out from the boot of a car, no drive to the woods. Without you they all give a story they agreed thirty years ago about meeting for a pint, and that’s if they even admit to being in Ruislip at all. Nothing changes. Do you understand that?’

‘I understand that if he knows I’ve talked, we’re not safe. Me or Gavin. I’ve told you everything I can, it’s up to you what you do with it, but please keep me out of it.’

She pulled her hand back and stood up, chair legs rattling as they scratched backwards. She took out her purse and dropped a ten-pound note on the table by their coffee cups.

‘I have to go. Please don’t tell anyone we talked. Especially not my husband. If he knew I’d been there … that I’d talked to you …’ She paused. ‘It would make things very difficult for me. For my marriage, and my son.’

She slid her glasses down from her head to hide the pain in her eyes, and left without saying another word. Porter watched her reflection in the mirror above their table, and wondered if his best chance – scratch that, Natasha’s best chance – to end this mess had left with her.