‘Let’s round off the evening by going on the river.’

‘No.’ Helen answered instinctively.

‘Come with me,’ Oliver said. ‘I want you to.’

‘Not the river,’ she persisted. She looked sidelong at Oliver and saw that his eyes seemed to have sunk back into their sockets. They were remote, expressionless. He was pulling her outside, away across the festivity of Tom Quad. His insistence and the vice-like grip on her arm made her think suddenly of the Ancient Mariner. The idea was fanciful but she shivered in her thin dress. She looked quickly around for Darcy, for Chloe and Dave, or even Scot Scotney, but there wasn’t one familiar face amongst the revellers.

Oliver was walking so quickly that she almost stumbled behind him. They reached Tom Tower and the stewards in the porter’s lodge stood back respectfully to let them pass. The night beyond looked pitch black and empty as the lights closed behind them.

‘Wait …’ she said, but he was deaf to her. They were almost out into the street when someone stepped in front of them.

A white jacket, and a rosebud against the lapel. Tom. Thank God. Helen felt her irrational fear subside. I won’t be far away he’d said, hadn’t he?

‘Oliver wants to go on the river,’ she gasped at him, breathless with relief. Tom took one look at Oliver’s face and the diamond-hard eyes in the deep sockets.

‘Why not?’ he said calmly. ‘We’ll all go. Where’s your wrap?’

The black velvet cloak appeared and she was hustled off between them into the night. The black Jaguar sat at the kerb directly opposite. Oliver swung himself into it and smiled at them, his teeth showing in white points.

‘A last romantic glide along the water and under the willows,’ he murmured. ‘Just the three of us.’

The Jaguar roared and plunged forward. Helen felt the bite of acceleration pressing her back against the seat and the firm warmth of Tom’s shoulder.

A corner, too fast, traffic lights, red, behind them now, another two or three dizzying turns and then a narrower road that bumped towards the black square of the deserted punt station.

Tom helped her out of the car. He was talking across her to Oliver, laughing, apparently unthinking. She pulled the heavy cloak around her to hide her shivers.

Over the dew-wet grass that soaked her thin slippers, they came to the river’s edge. The water was utterly black and still. A line of punts swayed almost imperceptibly from their moorings. Oliver vaulted into the nearest one and the ripples suddenly spread outwards, lapping under the boards of the landing stage. Tom materialised out of the dark with a pole and an armful of cushions.

‘You do the work,’ he ordered Oliver and passed the tall pole across the water.