‘So carry on as you are,’ said Webster, ‘acting as the somewhat put-upon and unappreciated dogsbody, and let’s see what Tindall does. Be less than careful about what you leave on your desk, and maybe ask him if you can use his safe. In this file’ – he passed a thick envelope under the table – ‘is all the information you need. You’re running a fictitious agent, code name Venice. You’re to arrange for Venice to be flown out next Wednesday night from RAF Tempsford in Bedfordshire and dropped north-west of Randers on the Jutland peninsula. The non-existent Venice will be on a Halifax from 138 Squadron; they’re part of the RAF Special Duties Service. We’ll make sure one of their aircraft does take off as planned – Tindall knows Tempsford well, and he may well check whether there was such a flight.’

‘And how do we find out if he’s passed the information on?’

‘The putative drop will take place near a village called Vorning. There’s a particularly trustworthy resistance cell in that area. It’s normally quiet, not many Germans. They’ll be instructed to keep a careful watch on the drop zone. If there are Germans out there waiting for Venice, then we’ll know Tindall’s tipped them off.’

Hendrie had played his part, even impressing himself in the process. He spent most of the weekend in the office, a fact that he mentioned to Tindall when he came in on Monday morning and which Tindall later verified with the porter who’d been on duty. He affected an air of preoccupation and even worry, dropping the Venice file, swearing profusely, then concealing it under a pile of papers. When he went out for lunch, he asked Tindall whether he’d mind if he kept something in his safe.

On Wednesday morning, he ensured his rail ticket to Bedford was visible on his desk, and when he left at lunchtime and Tindall asked him where he was going, he replied, ‘King’s Cross,’ before hurrying out of the office.

He spent the night at RAF Tempsford, watching the Halifax take off at nine o’clock, and was in the control tower when it landed after its thousand-mile return trip just before two thirty. Minutes later, the station commander, Group Captain Hanson, escorted him to the crew room, where the young flight lieutenant who’d been in charge of the mission described it rather in the way he might talk about a Sunday afternoon drive in his new sports car.