What made this room different from the rooms of most undergraduates was a complete lack of personal touches. There were no photographs, pictures, decorative objects, nothing, except piles upon piles of books on the subjects of nuclear physics and nuclear energy.

I began with his desk. In the first drawer was an assortment of bills, an invitation to an Oxford Union debate on nuclear power, and a packet of Fisherman’s throat lozenges. In the second drawer, on their own, were two telegrams. Both bore the same date: 10 August. One was from Otjosundu, Namibia; it said simply: Dadda pass away yesterday morning. Stop. He is more peaceful now. Stop. Love you son. Stop. Mama. The second was from Marzuc, Libya; it said: All has been agreed. Stop. Will be in touch. Stop. Lukas.

Most of the other drawers were filled with technical notes and papers. I scanned sheets at random, but there didn’t seem to be much of interest. It looked mostly like university work, but I couldn’t be sure as most of it was highly technical and way above my head. I photographed the sheets I pulled out, for the boffins at CCI to decide whether there was anything Tsenong was working on that he had no business to be working on.

I took each book off the shelf in turn, held it by the cover and shook it. Nothing fell out of any of them. I felt underneath the furniture, and went systematically through the entire list of possible hiding places: under the mattress, loose floorboards, cracks in the wall, everywhere – and nothing further turned up. Then I tried the most obvious place in the room: the filing cabinet. Inside the first drawer was a map of the world, with every nuclear power station clearly marked. I had no doubt that the map was an item he required for his studies, but I wondered for what particular reason someone had shaded in red pencil the whole of Britain, France, Spain, Canada and the United States of America. In addition, there was a flow of arrows around the world, and the flow struck me as looking not a bit unlike the flow of the January wind that I had studied earlier that morning. After the arrows passed through the shaded countries, they assumed the colour of the shading for some considerable distance. I photographed the map and replaced it. I went through the rest of the files, took a number of photographs, but did not come across anything else that struck me as being of particular interest.

I unlocked the door, listening carefully for any footsteps. This was always the moment I hated the most. I took a deep breath and marched out. The corridor was empty.