On top of her sturdy work desk, textbooks and folders were arranged with obsessive neatness. English, Geography and French. I flicked through them looking for hidden notes, but all I found was Post-it notes and a lot of colour coded highlighter pen. One thing was for certain, Olivia had no intention of failing her A-levels. With what her mum was like I didn’t blame her. Her bookshelves were interesting, pre-teen at the bottom mixed in with a couple of board games, older books above them – Roald Dahl, Diary of a Wimpy Kid and Harry Potter graduating up to Twilight, The Girls’ Book of Excellence, Malorie Blackman and, surprisingly, Zola’s Le Ventre de Paris in the original French. Because it stuck out, I opened it up and found it was full of pencilled notes in the margin – mostly English translations of difficult words. My French is actually worse than my Latin, but even I could tell that this was advanced stuff for an A-level student.

I went back to the collage and looked again – judging by the design of the frontage they were posing before, the picture of Olivia and her BFF in formal dress could well have been taken in a French city. A couple of the others definitely had Beaux-Arts architecture in the background – possibly France again. If I’d been standing in anything but a multi-million Mayfair terrace I might have been thinking of possible importation routes. But rich kids don’t need to hoof drugs over the border themselves. The rich have people for that sort of thing, and disposable people at that.

There were two mains sockets in the room, both with their own tangle of chargers and extension cords and I spent a couple of minutes matching them to her laptop, printer, her high end playbar, one spare for an iPhone that I suspected even now was being placed in front of the custody sergeant at Belgravia nick, and another spare that might have been for a different brand of phone. I made a note to check what Olivia carried, and whether it or a second phone had been handed in. A black lacquered wooden tray on the desk held paper-clips, a Post-it pad and scatter of USB sticks – those I decided to leave for the technical forensics guys from Newlands Park.

I sat on the bed, took a deep breath and closed my eyes.

I hadn’t found any controlled substances, or drug paraphernalia. It might have been hidden away, but if it was the follow-up POLSA team would find it. I couldn’t feel any vestigia in the room either. I’d always felt something with the various gods and goddesses of the rivers – even when they were reining it back on purpose – but there was nothing here apart from the usual background.