She was laughing, leaning forward to catch the end of a lengthy joke, when she heard some confused shouting, pounding feet and then the shiver and smash of breaking glass. There were a few ironic cheers in the supper room but no-one looked round. Then Helen saw Tom slipping past and the laughter faded in her. She murmured a brief excuse into the air and followed him.

Outside was a milling hubbub of people, nearly all men, some of them still laughing uproariously while others looked faintly shamefaced. The floor was covered with broken glass and dark with spilt wine. Then the crowd shifted a little and she stared downwards. At once the ugly little tableau burned itself unforgettably into her head.

Oliver was lying in an awkward heap with the smooth stuff of his tailcoat twisted round him. His face was white with red patches on the cheekbones and he was breathing noisily through his mouth.

Tom was kneeling over him, and the sharpness of his dark, intelligent face made the grinning heads around him look bloated and coarse.

Tom loosened Oliver’s white tie and turned his head to one side. Then he looked up at Helen.

‘Will you ask Maitland to come out and help me with him?’ he asked quietly. Helen whirled round but Maitland was already beside her with a white-jacketed waiter.

‘Leave it to us, please, sir,’ he said calmly to Tom. They bent down and took Oliver’s arms, then hoisted him between them. Oliver’s head rolled and he murmured something thickly. As they half carried, half dragged him away his feet tangled and bumped as if he was a huge doll.

Helen looked away, full of humiliation for Oliver.

Someone in the crowd brayed with laughter.

‘Whoops, there goes Mortimore again. Poor bugger’s getting past it.’

Guffaws broke out all round and the crowd jostled restlessly, uncertain of where to turn next.

‘What are we waiting for?’ someone else said. ‘The lake.’

They crunched over the broken glass and pounded away like clumsy dogs.

Helen became aware of curious faces peering out of the supper room.

Tom straightened up. He looked tired. ‘Come on,’ he said, very quietly, and led her away.

They crossed the mosaic floor of the hall in silence and wound up the shallow curves of the great staircase. In the gallery above they found a semicircular niche with a little padded seat between two marble busts.

For a moment they sat and stared at the light welling up from below. Helen could just see the silver star on top of the Christmas tree.

‘What happened?’ she asked at length.