Then, as Tibbot went to the kitchen to draw a glass of water, I suddenly had a thought. ‘I know where I’ve seen something like this,’ I said, jumping up. ‘At school.’

‘What do you mean?’ he said, coming back in.

I was overjoyed at the thought that we might now have it – we might be able to decode what she had been writing. ‘Library codes. To identify books.’

He nodded thoughtfully. ‘Library codes. Yes. Could be. Where’s your nearest library?’

‘Southwark.’

‘Better get there soon. If it’s open at all, it’ll probably close early for Liberation Day,’ he said.

We copied the codes on to a small slip of paper and put the book back in its hiding place. I had a hurried word with Hazel – with what was going on now, I thought it best if she went to a friend’s house and she reluctantly agreed to go. She had a key and could let herself back in for supper that evening.

Leaving the house after seeing her off, I saw a figure at the window of the house next door. She was perhaps twenty-two and dressed in a plain blouse and trousers cut like those you had to wear in the army, and her appearance made me suddenly very nervous. It must have shown, because Tibbot discreetly asked who she was.

‘Patricia. Our neighbour. She’s in the Party.’

‘Serious about it?’

‘Very. Nick told me to watch what I said around her.’ This slip of a girl could be as dangerous as the men who beat on your door in the night. So strange that raw muscle power – the power of men – was being quietly supplanted by the power of a whisper behind hands, a force that we women were better at employing.

Tibbot took my arm. ‘Well, try to keep calm,’ he said. ‘Don’t attract attention. Smile. Look around you. Stop to button up your coat. Just think of it as a normal day.’

He was right, of course: what we were undertaking was dangerous enough without doing anything to signal that we were engaged in something that made us nervous. After all, we were probably the only people in the city that day not happily getting ready to celebrate the arrival of the ship that had fired the first Soviet shot against the Germans.

‘Right. Yes,’ I said, and I did my best to smile.

13

I don’t remember the journey home with Nick from the Comintern party at the hotel, the moment when he, Charles and Lorelei had stared as the world had seemed to fall to pieces around me.