‘They’re just trying to do their job,’ she says levelly.

He exhales and runs a hand over his beard. ‘Let’s go to the office, then,’ he says, moving towards the front door. Margot follows. It’s raining now and they have to make a mad dash across the yard.

It smells damp as Adam opens the door, despite its insulation, as though nobody has inhabited it for a while. But the desk, as usual, is messy, papers, books and pens strewn haphazardly across it, with a half-drunk mug of week-old coffee standing by the monitor, spores of green mould floating on the top. Even the keyboard is covered with papers so that only the ends are visible. Adam looks mildly embarrassed as he rummages – no wonder he can never find anything, she thinks – until he comes to two A4-sized leatherbound diaries. He pushes them towards Margot. ‘These are 2011 and 2012, although there’s only a few pages marked in that one,’ he says.

Margot takes a seat at the desk and moves the debris aside, flicking through the pages of the 2012 diary. She takes out her reading glasses from the inner pocket of her gilet, slipping them on to peer through the list of names.

‘Right, well, I’ll get going,’ says Adam.

‘I’ll lock up,’ she says, without glancing up. ‘Come over for dinner later, if you like. You need to keep your strength up and I’ve got a casserole in the slow cooker.’

‘Thanks, Marg.’ He’s the only person who has ever shortened her name. It would annoy her coming from anyone else. But in Adam’s West Country burr it seems natural. She hears the door bang shut behind him as he leaves.

She licks her index finger before turning over the page. There aren’t many recent names on the list, out of season, so she doesn’t bother to read the first few pages of 2012. Instead she concentrates on the 2011 diary, flicking back to the summer when they were at their busiest. All the names of the customers who stayed on the campsite are there, in either Heather’s loopy writing or Adam’s more stilted hand. Sean and Sally Peeves, Caravan One, 6 August 2011, one week. Lawrence and Felicity Dawes, Caravan Two, 6 August, two weeks. Petra Anderson, pitch for one tent, four nights. It’s tedious work. And how far should she go back? They’ve been running this caravan park for nearly twenty years. Does she even have the old records? She recalls dumping a load of notebooks in the attic a year or so ago. Maybe she’d give them to the police and they could go through it all. And even if the Wilsons did stay here, what does it prove? That Heather knew them? But it doesn’t explain why she’d want to shoot them.