Cottesloe and Wickens allowed Elvira Hart a few hours to regain her composure before going to visit, which required negotiating the walkway over the East Molesey weir. Her home turned out to be an emerald green houseboat, adjoining a gaily painted raft crowded with planters of irises and gladioli. A dining table and chairs were set out among the greenery, beneath a parasol. The two constables crossed the gangplank from the shoreline and tapped the brass knocker on a door small enough for a Hans Christian Andersen tale. The woman who answered the door was what Cottesloe would have called a glamorous upper-class granny. Tall and slender, with refined features and clear blue eyes. She had evidently once been very beautiful. Her thick, shoulder-length, silvery hair had been expensively cut. The two officers were shown into a small but exquisitely furnished lounge, in which the morning sun reflected off a range of antique silverware. The two sat side by side on the chintzy settee, sipping proper coffee and eating artisan biscuits, as Ms Hart moved gracefully around them, plumping cushions and brushing imaginary specks from the arms of an antique chair before she sat in it.

‘You must have had an awful shock this morning,’ Cottesloe began, biscuit poised in front of his mouth.

‘It was horrible, actually. It was only just light, and this bloated, ghastly purple… thing floated up. I have no idea what must’ve happened to the poor chap.’

‘Well, we’ll leave that to the pathologist,’ Wickens said. He got out a printed map and asked her to show exactly where she’d found the body. The point she marked was exactly where CSI were now examining the scene.

‘Did you see anybody else around?’ Cottesloe said.

‘On the island? No.’

‘Ms Hart, in your initial call, you said you had just got back from a run,’ Wickens said.

‘That’s right.’

‘Do you normally go out jogging in the small hours?’ Wickens was a keen runner himself, but didn’t like to run at night.

She smiled. ‘Not normally that late, but it was the solstice and I was too hot to sleep. It was a beautiful night and I felt full of energy.’

‘And do you feel safe at that time of night?’ Cottesloe asked.

She laughed, an infectious tinkle. ‘Well it’s your responsibility to keep me safe isn’t it? No, I’ve never had any problems. I take a small torch with me. I can run quite fast, and have a loud scream, should I need it. There are plenty of houseboats around if I do need help, and a boyfriend lives on the next island.’

Wickens noted the phrase a boyfriend, leaving room for more. ‘Ms Hart, honestly we wouldn’t advise running in darkness. There have been incidents over the years.’

She smiled again. ‘Your advice isn’t surprising since you’re a policeman. Every day you are surrounded by evidence of the worst that people can do.’