I remember it all: the incessant questions sometimes yelled, others whispered into my ear, the beatings, the suffocations, the rapes.

But the details don’t matter.

What matters is ... I held my silence. During each session, I drifted from my body to watch and not speak. The interrogation was days long – two, three ... four? I lost count.

In the grey dawn of a morning, the cell door crashed open. A guard threw down beside my naked body striped pants and a jacket with a large red X on the back. “Dress.”

The material was coarse and grated across my damaged skin. I struggled into the pants with difficulty: I was stiff and aching. The guards grabbed me and one forced my arms into the jacket, ignoring my groans as he stretched damaged muscles and torn skin.

At the rail yard, they shoved me into a cattle wagon full of women, slamming the door behind me. The women saw my battered condition and tried to ease my pain. We were in that wagon for two days with neither food nor water, sometimes clattering along but also stationary for hours on end. When they slid back the door one afternoon and yelled at us to get out, we found the guards were women.

Pushed and prodded, threatened by slavering dogs, we shuffled towards the gates of a compound. Inside, we stood in ranks, shivering in the icy wind blowing off a nearby lake.

A guard spotted the red X on my jacket, calling out and pointing at me.

They hauled me out of line – a special prisoner, it seemed – dragged me across to the main camp building where I ended up in another bleak cell.

In the morning, a girl in the striped prison uniform worked her way down the cells, emptying our stinking slop buckets accompanied by an SS guard. Later, she brought a meagre amount of food and water to each of us. We shared brief, furtive looks through the meal hatch before I tried speaking – but she understood neither English nor French.

I pointed to myself. “Englander.”

What was the German for French?

She blinked and checked down the corridor, wary of the guards, and then pointed to herself. “Deutsch ... Frida.”

She was German. What had a German child done to warrant imprisonment in such a place?

I pointed to myself. “Colette.”

She glanced sideways again and scrambled away as I heard boots approaching.

Over the following days, Frida’s stops at my meal hatch lengthened. We held frustratingly broken conversations, learning words in those stolen minutes. The day after I arrived, she told me of two other Special Operation Executive girls in the cells by pointing to me and then down the corridor twice. A week later, I was the sole remaining SOE girl. Accompanied by a strutting SS officer, guards dragged the two past my cell and through a door at the corridor’s end. I heard two gunshots.

At least they hadn’t died alone...

But time with Frida was minutes in long hours of isolation. Dr Johnson had quipped that the knowledge of impending execution concentrated the mind. I set out in what time I had left to relive my happy memories.

I slipped away from my dank and freezing cell to ... picnics in the Bois de Boulogne and the gardens at Versailles, to strolling with my parents beside the Seine in the shimmering wet streets of Paris. I relived glorious summer days with my cousins on the beaches of Normandy – memories now clouded by the knowledge of the furious battles fought there just months ago.