I started laughing too. What the hell were we doing? We splashed our way out of the water and I wrapped Charlie in the robe before hurriedly pulling my own clothes over my wet skin. I pulled Charlie against me and felt her trembling.

‘Let’s get—’ I began, then stopped.

‘What is it?’ she asked.

I stared into the trees that ringed the lake, peered into the shadowy spaces between them, and said, ‘Hello?’

Charlie followed my gaze, her eyes wide.

‘Did you see something too?’ I asked. When she shook her head I said, ‘I’m sure there was someone there, watching us.’

‘Oh please, don’t.’

Tentatively, I approached the trees. There was no one there.

‘Let’s get out of here,’ I said. My whole body felt like it had been encased in ice for a thousand years, like that Stone Age man they found in the Italian Alps. And right now, I needed to get back to the warmth and safety of my cave.

I was still thawing out half an hour later as Charlie and I sat at opposite ends of my bath. A gentleman, I had taken the end with the taps and the plug. Soap bubbles covered Charlie up to her shoulders. She took a sip from her condensation-streaked wine glass.

‘I still can’t believe we did that,’ I said.

She laughed. ‘Me neither. It was fun though.’

I wasn’t sure if that was the right word. It was intense, unforgettable – but fun?

‘I wasn’t wearing a condom,’ I said.

She scooped up a handful of bubbles and blew them at me. ‘You’re such a worrier. It’s OK. I’m on the pill. And I’m trusting that you’re not wildly promiscuous, so your chances of having a disease are low.’

‘I’m definitely not, nor have I ever been, wildly promiscuous,’ I said.

She paused, took a sip of wine. ‘So, what’s your number?’ she asked.

‘You mean, how many women have I slept with?’

She smiled. ‘Uh-huh.’

‘Seven,’ I said, after taking a few moments to count in my head. ‘Including you.’

I had expected her to say something like ‘is that all?’ because, compared to most of my friends and from reading survey results in magazines, mine was a low number. But she said, ‘I know Harriet already, and me of course. Who were the other five?’

I ran through the other girls.

The first had been Laura, my girlfriend when I was in the sixth form at school. We were both virgins and after many heated petting sessions, finally went all the way while babysitting a neighbour’s toddler. We stayed together for another few months after that, splitting up when we both went to university.

There were Junko and Helena, two one-night stands when I was a student.