I made my way downstairs, through the cold, empty, black halls of the out-patients' department. It was a bitter night outside, with sleet falling heavily and freezing immediately on the pavement. There was no one in sight except a porter sweeping in the distance in the thin light of a lonely bulb. I suddenly felt that I was the only doctor in the world.

I found the patient sitting under a blanket on an examination couch. He was a thin, neat-looking man in a blue suit and a white collar, with a small moustache, carefully-brushed hair, and horn-rimmed spectacles. He looked worried, but unfortunately not like an immediate candidate for the operating table.

'Well now, what's the matter?' I began, as briskly as possible.

'I'm extremely sorry to have troubled you, Doctor. Extremely sorry indeed.' He spoke quietly, with a faint Cockney accent. 'I have took you away from your no doubt well-earned repose. I apologize, Doctor, and ask your forgiveness for that which I have done.'

'That's quite all right. It's what I'm here for.'

'I said to myself as I came in, "The doctor is now, no doubt, reclining in the arms of Morpheus. He is sleeping the sleep of-"'

'What's the matter with you, please?' I interrupted.

He suddenly clutched his abdomen with both hands and groaned.

'Abdominal pain?' I said, flicking the pages of my surgical text-book through my mind. 'Colicky, no doubt? Any relation to food?'

He relaxed, looked round, and whispered, 'Are we alone, Doctor?'

'Alone? I assure you, professional confidences will not be divulged.'

'You're the Professor's house surgeon, ain't you, Doctor?' I nodded. 'Well, Doctor, it's like this here. The Professor operated on me six months ago-partial gastrectomy, up in Faith Ward. All was well, Doctor, until three days ago. Then I began to have pains.' He groaned as another spasm caught him. 'Something shocking, Doctor. Tonight, after a bite of supper, I coughed and found something hard in my throat.' He glanced over his shoulder again and whispered, 'It was a nut, Doctor.'