Tom paid for the items using his untraceable card and they left the store, got into the car and drove back to the hotel. Once there, Tom unpacked his purchases and began sorting through the electrical items.

‘You going to share the plan with me?’

‘I’ll show you once it’s done. You probably won’t believe me otherwise.’

Tom took out a roll of cable with a jack plug at each end, the type that would be used to connect an electric guitar to an amp. He stripped one of the plugs and took a small electrical component from the bag.

‘What’s that?’ Pet asked.

‘It’s a photodiode, it focuses light into this sensor. Now, please let me work; I need to remember how to do this.’

Pet feigned hurt and turned to her laptop screen.

Tom got out a roll of lead strip and a soldering iron, which he plugged into the wall socket. He soldered the connection terminals onto the exposed jack plug wires, filling the room with the smell of scorched lead.

He used insulation tape to secure the end of the lead where the photodiode was exposed, and taped the whole thing to the top of the full-size tripod. He then removed a small pen-shaped object from a blister pack and connected it to the smaller tripod using a plastic G-clamp.

‘A laser pen, before you ask. Do you have audio software on the Mac?’

‘Of course. It has Wavepad installed. I can record and manipulate sound however you like on it.’

‘Perfect.’

He went to the window which looked out onto the main road. In direct line of sight was a row of 1930s semi-detached houses about a hundred metres away. Perfect for the test, thought Tom, picking up his binoculars. Fortunately, the weather was dark and overcast.

He took the smaller tripod and set it on the window ledge, pressing a switch on the side of the laser pen. He began making slight movements while looking at the houses in front with his binoculars.

‘I didn’t know you were a Peeping Tom, Tom.’ Pet smiled at her own joke.

‘Look at the wall behind us and tell me when you see the reflection of the laser dot.’ He began adjusting the pitch-and-tilt function of the tripod.

After about five minutes, Pet said, ‘It’s here now, four feet up the wall.’ Tom turned and saw the laser dot on the wall behind them, clearly visible. Perfect.

He took the larger tripod and lowered it so that the electrical component was visible, facing forwards by lightly bending the connector strips upwards so it resembled a forward-facing torch. Tom carefully adjusted the tripod’s height until the laser dot hit the photodiode face.

Holding the other end of the wire, he took a jack plug adapter from his bag, snapping it into place so it was compatible with the headphone port on the laptop.