Once the office lights were out and the blinds at the rear adjusted to shield the moonlight, Henderson gathered his saucers of chemicals in tight formation, leaned forwards over the desk and flipped the jacket he’d been carrying in his suitcase over his head, protecting his equipment from any remaining light.

Marc watched as Henderson fidgeted mysteriously beneath the jacket and the sweet smell of developing fluid filled the air. He stripped the rectangle of photographic paper from the camera and counted the ticks of his watch to ensure it spent the correct time in the developing fluid.

Marc had no idea how long it would be before Henderson emerged with the developed photograph. He thought of asking, but didn’t want to affect Henderson’s concentration.

‘Have you ever made a cup of tea, Marc?’ Henderson asked, once he’d moved the sliver of paper from the developer into the bleaching solution.

‘Sorry …’ Marc said weakly. ‘I’ve never even drunk it.’

‘You’re a blank canvas, Marc Kilgour,’ Henderson laughed. ‘You go upstairs, put a kettle on the stove and I’ll show you how to make a proper English cuppa while your picture dries.’

‘What’s a cuppa?’ Marc asked, liking the word, even if he wasn’t sure what it meant.

Henderson trembled with laughter beneath the jacket.

He didn’t laugh for long, though. Both phones had stopped ringing, but it became clear from a loud scuffling sound that something was happening on the steps out front.

‘Those gendarmes must have heard us breaking in,’ Marc said anxiously, as the metal gates over the front door whined for a shot of oil. ‘I bet it was them on the phone.’

Henderson remained calm. ‘Ignore your emotions and use your brain,’ he said firmly as he pulled his head out from beneath the jacket. ‘The police don’t phone up and ask burglars if they’d be kind enough to leave and the Germans certainly wouldn’t tip us off with a fracas on the doorstep. I just need half a minute now to fix the image. Go up to the front window and tell me what you see.’

Marc vaulted the counter and dodged two lines of chairs in the waiting room, then peeked through a tiny crack in the velvet curtains. A white Jaguar sports car had parked up on the cobbles and an anxious crowd hassled its female driver as she unlocked the gates.

‘Guessing it’s someone who works here,’ Marc hissed. ‘She’s got keys and everyone in the queue’s giving her stress.’

Marc could hear what was being said, but it was all in English so he didn’t have a clue.

‘I have urgent consular business,’ the woman yelled. ‘You all need to come back in the morning. We’re open normal office hours. Nine to five and noon on Saturday.’