In the troubled water above the sluice-gates, half a dozen swans were waltzing with slow grandeur, swinging round with the current, backing and then, effortlessly, gliding into position again. Above them, perhaps twice as many gulls hung in the radiant air, curved and dipped, swooped and soared, counterpointing the graceful galleons below. It was something to see: Nature tricked into art.

‘See how they dance together,’ Irina said. ‘All part of the same pattern.’

‘It’s very impressive,’ he said. He pointed across to the Quai des Bergues. ‘With a very simple motivation.’

Two women were standing there, tossing scraps of food into the river. The gulls were trying to take them on the wing; where they failed, the swans were ready to snap up the pieces as they reached the water.

‘It may look like a dance,’ he said, ‘but it’s a battle.’

Irina stared down at them. She said: ‘I wish all battles were like that. So beautiful, and with no more to lose than a few scraps of food. They don’t look hungry even.’

‘Swiss swans,’ he said, ‘and Swiss gulls.’

‘The gulls …’ she said, ‘the way they circle above the swans – as though they were blessing them.’

‘Be not deceived. There’s nothing angelic about a gull. All they want is to intercept the food before the swans can get it.’

Irina shook her head. ‘So beautiful!’ she repeated. ‘As though they are conscious of their innocence.’

‘Yes. Never trust innocence.’

She looked at the flying and floating birds without replying. Then she turned away and Hibson went with her. They came out on the Quai, and he steered her across the road.

She said, in a low voice: ‘Why do you say that?’

They entered a side street. He put his arm round her waist and her body yielded.

‘Innocence is appetite,’ he said, ‘ruthless when it finds something to feed on.’