The police officer who arrested them both introduced himself as Superintendent Prince. He was somewhat younger than she’d imagined someone of that rank to be, but he was very civil towards her – even quite pleasant, if the truth be told. In the few hours she had to herself in the cell at the main police station in Lincoln, she had plenty of time to reflect on her predicament and refine her story. She knew she had to ensure it was consistent, and by the time she was escorted into the interview room, she felt she was prepared. She was going to tell how the man had broken into her cottage; how he’d threatened her and prevented her from leaving. She would tell them she couldn’t describe how relieved and grateful she was that they’d come to rescue her. She would also address the inevitable question before it was asked: of course she had never been involved in politics. She was not a Nazi sympathiser. She was a British patriot. Her husband had been killed at Passchendaele, after all. She had no idea whatsoever why her cottage had been targeted; perhaps because of its proximity to the beach.

Before she could speak, however, the polite young superintendent calmly set out the evidence against her. He told her how they knew the German had landed by U-boat the previous Monday morning. They knew a call had been made to a contact in London later that day to signify his arrival; that call had been traced to a telephone box very close to the school where she worked, and the caller had been a woman. He believed that woman to be her. The phone call, he said, checking his notes, had been made at a time when the headmistress of her school confirmed she’d left the premises. He pointed out that she’d had plenty of opportunity to go to the police but had failed to do so, and he told her they knew she’d previously been involved in the British fascist movement.

She tried to hold her nerve: it looked bad, but she wasn’t sure if that amounted to much in the way of hard evidence against her. She felt her story still sounded feasible. She was about to recount it when Superintendent Prince held up his hand – one minute, please.

‘Clearly, we wish to hear your side of the story, but let me tell you this, Mrs Abbott. If you confess now and tell us everything, I can promise you will be treated with a degree of leniency. We would consider a lesser charge than treason.’

He paused to let the words sink in. She felt sharp prickles of sweat and fear all over her body.

‘Treason carries the death penalty, as I’m sure you’re aware. With a lesser charge and a guilty plea, you’ll be surprised at how relatively short the prison sentence could be.’