Prince interrupted his Chief Constable. ‘There’s not much around there apart from fields and sand dunes – and it’s very open, nowhere for him to hide. But I don’t think he’d have got far. He must have had some help; he’s most likely to be in a safe house.’

‘We need to find him. Can’t have a German spy wandering around, can we? Until now we’ve been reluctant to do anything that would attract attention. We gave him the benefit of the doubt: perhaps he was exhausted after coming ashore, maybe he needed to keep his head down for longer than planned, possibly his journey to London was not as straightforward as he’d hoped. It’s even possible he was injured, who knows? But it’s Thursday now, he’s been in this country for the best part of four days and we want to know where the hell he is, not to put too fine a point on it. My sense is that for whatever reason, he has not got very far. He may well be too frightened to move from his safe house. But we need to be careful; we don’t want word getting out that a Nazi spy is on the loose, do we?’

There was a long silence. From somewhere in the room a clock ticked noisily; the only other sound was the Chief Constable clearing his throat. Richard Prince stood up and walked over to a large framed map slightly askew on the oak panelled wall. The man with the Scottish accent joined him, the Chief Constable eventually moving in behind them. Prince studied the map carefully before speaking.

‘There are two obvious ways out of the Mablethorpe area: by road or by rail. Even by road it’s a long way to anywhere and I’d have thought it risky. The area’s teeming with army camps and RAF stations; there are roadblocks and patrols everywhere. He’d be exposing himself for far too long going that way. You say you think the plan was to arrive in London by train?’

‘Only because it makes sense with the pub on the Caledonian Road being the rendezvous point.’

‘It would certainly be wise for him to use the rail network. There’s a station at Mablethorpe, on what they call the Mablethorpe Loop. There are four or five trains a day in either direction. He could either have gone north to Louth and from there connected to a mainline station such as Lincoln, or – which I think more likely – gone south to Willoughby, where at least one train a day connects with the Cleethorpes to King’s Cross service.’

‘How long’s the journey?’

‘From Mablethorpe to Willoughby? A quarter of an hour.’

‘And what would security be like?’