‘Heil Hitler,’ a bespectacled German said, when he saw Henderson. ‘What can I do for you, Major?’

‘Are the telephone lines working?’ Henderson asked bluntly.

‘We’re having difficulty. Many staff didn’t come to work because of the curfew,’ he explained. ‘We only have four French operators out of more than sixty. Calls within the city work through the automated exchange, but long-distance calls require manual connection. The operators can’t cope, so I’ve restricted long-distance calling to military traffic.’

‘I need a connection to Tours,’ Henderson explained. ‘Is that possible?’

‘I’ll speak to one of the operators. We have connected some calls to Southern France successfully, but the network is very busy. It can take a long time and some local operators are disconnecting anyone they overhear speaking in German.’

‘My French is good,’ Henderson said. ‘Tell the operator to start making a connection to Tours immediately.’

‘Yes, Herr Major,’ the engineer said, before striding purposefully towards a woman at a manual switchboard.

Henderson stepped over to a metal shelf and grabbed the two bulky directories that contained every telephone number in France. He flipped quickly through the pages until he found the listing for Tours. The town had more than 100,000 inhabitants, but less than 2,000 had telephones.

Henderson turned to Marc as he pulled a fountain pen from his uniform and unscrewed the cap. He looked around to make sure the engineer was out of hearing before speaking in a whisper. ‘Can you read and write?’

‘Course I bloody can,’ Marc said indignantly.

‘You scan the right-hand page, I’ll take the left. I want you to take out any phone number that’s for a church or a religious organisation. Or anyone listed as a priest or a minister.’

‘But how will we know which one?’

Henderson shook his head. ‘We won’t. But priests, rabbis and other ministers within a community usually know one another. If we can get a couple of calls through, the chances are they’ll know about the retired priest who took in two children and be able to pass on a warning message. Even if they don’t know him, they’ll know of someone who does.’

‘That makes sense,’ Marc said, nodding. ‘But aren’t priests too poor to have telephones?’

‘That could be a problem,’ Henderson acknowledged. ‘But we only need one man, even if it’s the Bishop of Tours himself.’

The pair began running their fingers down the listing of Tours telephone numbers. Each page took a minute to scan and when they’d both finished, Henderson would flip over to the next.

After four pages the German engineer approached. He pointed to the pretty operator seated at a switchboard twenty metres away. ‘Marte is trying to establish a connection. She rates our chances of getting through at about fifty-fifty.’

‘Thank you,’ Henderson said, curtly. ‘I’ll call if I need you again.’