‘I love it here,’ sighed Dovidl luxuriously.

‘But you wouldn’t want to spend your life in a place where no one ever grows up,’ I countered.

‘Why not?’ he mused. ‘It’s safe and sometimes warm. It’s a haven.’

‘From what?’

‘Oh,’ said Dovidl vaguely, ‘you know . . .’

I did not know, but could not admit it. I suppose he meant the gambling and the whores, the guilt of being alive, the terror of dreams. I was preoccupied with the topic of my dissertation and displayed little curiosity in his escapist fantasy. I felt like asserting my independence of mind. He had no right to disturb my thoughts without warning. I was his friend, not his agent – not yet, at any rate. He did not have automatic first call on my mind.

Should I have given him the full beam of my attention? Pressed him to elaborate? Nursed him through a patch of insecurity? The omission would return to nag me through many sleepless years.

We each won a research grant at the end of the first year, and the Master of John’s hinted over a glass of dry sherry that a fellowship was mine for the taking. I flushed with satisfaction. While most of my former classmates were square-bashing in the British Army and saving ration coupons to buy a bottle of cheap booze, I was being ushered into a life of learning and the vintage comforts of high table. It was a passport to privilege. I could make my name as a scholar, stamping my authority on a period in history while teaching grateful generations of acolytes. Yet I would not be tempted by the orange winks of college life unless Dovidl, who had been made a comparable offer, signalled acceptance.

‘What do you reckon?’ I asked.

‘No hurry,’ he said lazily. ‘We have another couple of years before we need to do anything so strenuous as making a decision.’

‘Is Toytown growing on you?’

‘It has its moments,’ winked Dovidl, suggesting he had got lucky with some Girton bluestocking. One way or another, he had got over that starlit wobble without my intervention.

Nothing else had changed: my tail was hitched to his comet, to follow where he blazed. Together, we would take on the world – that is what he had pledged. So when, the week before Christmas 1949, I came home to Blenheim Terrace and heard him playing Bach with a fervour that had been missing since the war ended, my heart skipped a beat and I was overcome by anxiety.

‘What’s going on?’ I demanded, barging into his room.

‘I’m back on the fiddle.’ He grinned.

‘I can hear that. Why?’

‘I need some spare cash.’ He laid the Guadagnini crookedly in its case and lit a cocky cigarette from an exotic pack.

‘Are you in trouble?’ I quavered.

‘Nothing I can’t handle.’

‘Meaning?’