‘Harold Hamilton rings a bell,’ said Prince, frowning.

‘Not for me, I’m afraid,’ said Harper.

‘The forger who was arrested in Manchester: didn’t he provide a list of false identities he’d provided and try to have his charges reduced by telling us that one of his clients bore a striking resemblance to Edward Palmer – the Nazi agent code-named Milton?’

‘Good Lord, Prince, you’re quite right. No one believed him at the time, did they? We thought it was just an attempt to curry favour. What was the identity he said he provided for Palmer?’

‘That’s the point, sir – it was Harold Hamilton: the forger said he sold it at a premium.’

It was the time of year when darkness descended in the afternoon with a suddenness that turned day into unexpected night. When Hugh Harper turned on his desk light, all four people in the room looked shocked. They had now established a connection between Edward Palmer, the fugitive Nazi spy who’d worked in the War Office, and a woman associated with the group of Nazi sympathisers apparently helping to fund the Nazi escape line. For a few moments they sat in silence as they absorbed this.

‘We shouldn’t arrest her tomorrow, Bartholomew.’

‘Whatever do you mean, Roly?’ Hugh Harper looked confused.

‘I agree with Sir Roland,’ said Prince. ‘We know that this Myrtle Carter and Edward Palmer are planning on travelling to the Continent with at least two hundred pounds. If we arrest her at the bank, we lose him. If we follow her to wherever they’re living, we might arrest them both but…’

‘…we lose the trail of the Kestrel Line,’ said Pearson. ‘Prince has got it. Bartholomew, you need to have a top team on this, and even then we’re running an enormous risk. We need to keep an eye on her as far as possible, but the priority is to find out exactly when and where they’re crossing the Channel and then follow them to wherever they’re headed. With some luck they’ll take us to Turin – and maybe even Martin Bormann.’

‘And Hanne,’ said Prince, his voice quiet. He was clearly upset. ‘With some luck they’ll lead us to Hanne.’

By the time Prince left MI5 that evening, his journey to Austria was taking shape. He’d be on an RAF flight in the morning to the US Air Force base in Munich, and would travel on to Villach from there.

He was staying at a MI6 safe house in Holland Park, and as it was a dry and not too cold evening, he got off the Underground early at Notting Hill Gate to walk the rest of the way. He wanted to clear his head: he ought to return to Lincoln to see Henry before travelling to find Hanne, but as much as he felt drawn towards his son, he felt he couldn’t risk delaying his search for her by even one day.

He turned into Addison Road, which despite its size felt as quiet and isolated as a country lane. He stepped aside to allow a couple walking their dog to pass, and was annoyed when they slowed down in front of him. He was about to cross the road when a man came alongside and positioned himself between him and the kerb. Prince turned round: another man was close behind him, a hand menacingly inside his coat pocket.