‘Well, you may have just seen it yourself,’ Wickens said.

‘Possibly. But the risk is that fear informs a life of constrained choice and curtailed freedom. By contrast I have lived my entire life sustained by a belief in the best that people can do, the best that they can be. I am rarely disappointed.’ She reached for her own coffee, and the long sleeve of her sweatshirt rode up for a couple of seconds before she brushed it down.

‘When you were having your run, were you aware of anything unusual? Were there other people around?’ Wickens asked.

‘Yes, there were a surprising number of people around in Hurst Meadows park, considering the time. Late-night picnics, carousers, young lovers. It made me think of Sisley’s paintings, you know.’

‘The French impressionist?’ Cottesloe asked. ‘I think he’s the best of the bunch.’

Wickens glanced at his colleague appreciatively. Hidden depths. First obscure songs, now this.

‘He was British, actually, though he lived most of his life in France. He lived around here in the 1870s. I’ve got a delightful print of his Molesey weir painting in my bedroom. It’s a gorgeous melange of aquamarine and whites, with a thick impasto sky. Take a look if you like.’

Cottesloe paused, his eyes unfocused as if considering.

Wickens jumped in: ‘Anything else unusual you noticed, Ms Hart?’

‘Yes, there had been some noise. There was a party on the other island…’

‘Tagg’s Island?’ Cottesloe asked.

‘Yes. I’d been there earlier myself. It was the usual Kretz solstice bash and carried on a bit after midnight. As I was on my way home I also heard some awful music pounding out of a car on the bridge. That racket must’ve lasted until almost two. That’s really why I decided to go for a run.’

‘Did you get a look at the car?’ he asked.

‘Well, it was a white BMW with a personalised number plate.’

‘Did you write it down?’ Cottesloe said.

‘No, but I might recognise it again if you showed me. There were three people there, in the car with the doors open.’

‘Can you describe them?’

‘The two in the front were black, one was quite a big guy.’

‘Did you approach them?’

She shook her head. ‘No. I wasn’t angry or anything, I just thought it a little inconsiderate.’

Wickens said: ‘How do you get back from a party on Tagg’s Island? There’s no bridge between the islands.’

She laughed. ‘By boat. I have a little motorboat, although in the past I have swum it. It’s only fifty yards. When there is a drought you can even wade it.’