At the safe house there was a message from Gilbey. Change of plan: there’s a flight to Munich at three in the morning and you’re on it. A car will pick you up in half an hour.

He was driven to RAF Benson in Oxfordshire and flew from there on an RAF DC3 to Neubiberg airport just outside Munich, where he was met by a harassed British liaison officer called Cuthbert who assured him he was working on getting him to Klagenfurt. ‘Shouldn’t take terribly long.’

‘To get to Klagenfurt?’

‘Uh, no… to work out how to get you there. We’re rather dependent on the Americans here. No rush, though, is there?’

Prince explained that actually there was a rush, but knew better than to rely on this man to expedite matters. He wandered around the airbase until he found the officers’ mess, where he joined a table of USAF pilots to whom he explained his dilemma. I need to get to Vienna.

‘Is this official British business?’ The man who asked the question was young and wearing dark glasses, and spoke with a long cigarette clamped between his front teeth. Prince assured him it couldn’t be more official.

The pilot stood up, towering over him. ‘Follow me.’

He’d arrived in Vienna just before noon, and in the eight hours since then had wandered round the city knowing he’d only see the Russian when Gurevich was ready to be seen.

Don’t worry about finding him, he’ll find you.

And now Gurevich was ready. They made an unlikely pair as they walked through Vienna’s First District, one in a British Army greatcoat, the other in a Red Army one. They walked past the magnificent St Stephan’s cathedral, which seemed to throw shadows even in the dark. Gurevich’s pace quickened as they turned into Dominikaner Bastei, seemingly heading towards the Danube Canal, and Prince wondered what would happen if they crossed from the neutral First District into the Soviet zone.

Gurevich stopped just before the junction with Schwedenplatz. He looked round as he lit a cigarette, pausing to allow two Austrian police officers to pass. Moments later, Prince found himself in the basement of a bar, furniture piled high at one end, the bare room lit by a single bulb. Gurevich sat down opposite him at the solitary table.

‘Hanne’s safe.’

Prince gasped and stared intently at the Russian in an attempt to work out whether he was telling the truth.

‘You look like you don’t believe me, my friend. Why would I lie?’

Prince coughed and realised tears were forming in his eyes. ‘It’s not that I don’t believe you, but… maybe this is just what someone has told you… maybe they’re wrong… How do you know she’s alive?’

‘Believe me, I know.’

‘Has she escaped from the Nazis, or been rescued?’

‘Who said she was with the Nazis? In our business we shouldn’t make assumptions, should we?’

‘Don’t play games with me, Iosif, I need to find my wife. Where the hell is she? I need to know if she’s safe!’