Pre-concert tension claimed other casualties. The composer Kuznetsov was rushed to hospital with high blood-pressure, which returned mysteriously to normal the moment my father turned up with a missing page of his new concerto. The conductor, a crabby refugee called Matthias Freudenstein, stabbed his hand with a baton in his rage at the alleged illegibility of the full orchestral score. A trombonist turned up fighting drunk; his replacement demanded a bonus for playing a long solo. The Albert Hall bar staff walked out over some imagined grievance, and walked straight back in again when their exit was blocked by a semi-retired heavyweight boxer, Gordy Mills, whom we had hired to stand guard at the artists’ entrance.

Scotland Yard sent round a flat-hatted inspector to discuss crowd control. The St John’s Ambulance Brigade doubled its complement of first-aiders. My mother began having hysterics about her post-concert reception, which a distant Norfolk cousin of the Queen had graciously consented to attend. ‘When do I curtsy,’ she quavered. ‘And do I call her Your Royal Highness?’

As the frenzy mounted, the calmest man in sight was (David) Eli Rapoport, the object of all attention. Dovidl was unruffled, so far as I could tell, and I could tell better than anyone. He breezed through rehearsals and interviews with a quip and a smile. He had time for mid-morning coffee, and for nights on the town.

‘Getting enough sleep?’ I asked, mock-solicitously.

‘A man’s got to do . . .’ He winked.

‘. . . what his manager tells him to.’ I laughed.

Looking back, I have asked myself a thousand times whether his was a preternatural calm, camouflaging a premeditated defection. Try as I may – and I have tried hypnotists, holistic healers and two Jungian psychoanalysts – there is nothing I can recall in his conduct during those last days that suggested anything sinister or destructive. But, then, Dovidl wore his nonchalance like a shield. He was the antithesis of the highly strung artist who goes amok when an old lady coughs in his concert or an oboe comes in late. Dovidl seemed to take life as it came – took what he wanted, and left me to cope with the residue.

So when the police, among others, came asking questions after he vanished on that milky-May morning off the face of the earth, I as his closest confidant was unable to assist with their enquiries. I was as dumbstruck as anyone by his disappearance, devastated by loss, guilt and the smack of betrayal. Where had I been when he was vanishing into the void? Working flat-out, like everyone else, to put his name up in lights. I saw nothing, heard nothing, sensed nothing untoward – except for one jitter of anxiety as he climbed into the taxi and I called out, ‘Dovidl, are you going to be OK?’ He assured me that he would be fine on his own, back soon.