Jonas Kaufmann: Tenor for the Ages, BBC Four review - a musical megastar with sword and shortbread

Now we know who sent Jonas Kaufmann the Union Jack boxer shorts for the Last Night of the Proms. Whether the sender’s identity is the bigger surprise, or the hint of ambiguity over whether the "Greatest Tenor in the World" had previously heard of one of Britain’s favourite baritones – well, you decide. And no, we don’t learn who threw the knickers at him from the arena.

It’s all good clean fun in the Jonas Kaufmann show. The Last Night of the Proms 2015 was just one incident in an action-packed two years for the German opera star, whose popularity currently sweeps all before it. The documentary director John Bridcut and his team shadowed him for much of 2015-17: choosing his favourite shortbread at Fortnum and Mason or plopping bags of gummy bears on the dressing-room table; disguised in woolly hat to cheer for his beloved home team, Bayern Munich, or undergoing a tongue-stretching throat massage. And throughout, there’s that voice, Kaufmann’s oak-strong, coffee-dark, ultra-controlled deep tenor tone, whispering Verdi, eloquently expounding Britten, belting out Wagner. 

To those who chastise him for cancellations, he responds 'Mind your own business' 

Kaufmann devotees will recognise many of the incidents. The Barbican celebration that was snuffed out by bronchitis. The period in which a burst blood vessel on his vocal cord stopped him singing for some five months – implicitly it may have involved the altitude at Machu Picchu. And the Vienna Tosca in which the audience wouldn’t let him go without encoring “E lucevan le stelle” – only for his Tosca (Angela Gheorghiu) to miss her entrance. Kaufmann stopped the show again with an improvised line: “Ah – non habiamo soprano!” (“We don’t have a soprano…”). He and said diva, Kaufmann tells the camera, disagree over whose fault that was.

He comes across as a live wire, with a sharp mind that sometimes proves “intimidating” to opera directors and conductors, mitigated by a (mostly) ready laugh. Still, he doesn’t suffer fools gladly. To those who chastise him for cancellations, he responds, “Mind your own business,” while reminding us that nobody would insist an injured footballer should press on with the game regardless.

As a performer, though, he goes extra miles, sometimes literally. A spat over how to lose the handkerchief in the Royal Opera House's Otello holds up a rehearsal for 15 minutes; tempers fray all round. Then, waiting in the wings to begin his debut performance in the role, he suddenly sprints back to his dressing room, leaving the company terrified he won’t make it to his entry (he did). Reason? He forgot his sword. Why not sing without it? “‘Esultate’, without the sword?” Kaufmann seems scandalised at the very notion.

It’s an intimate portrait – if only up to a point. Dressing-room preparations, strolls with his girlfriend Christiane Lutz, and a visit to Aldeburgh (he’d like to sing Britten’s Peter Grimes) build up a pretty enough picture. His colleagues – such as the conductor Tony Pappano, his pianist Helmut Deutsch, the soprano Eva-Maria-Westbroek – praise him to the skies. Telegraph critic Rupert Christiansen says he looks like Jesus Christ. Yet we learn little about his background or family past or present (there’s one passing mention of his children). The film shows much of Kaufmann the star, but only tantalising glimpses of the man beyond the gummy bears.

Even if, inevitably, this feels like carefully authorised biography rather than fly-on-the-wall reality, it’s still a lively and heartwarming hour and a half, beautifully filmed and with splendid recorded sound. Kaufmaniacs can relish it on the iPlayer for a month of unlimited repeat viewing.

• More TV reviews on theartsdesk

@jessicaduchen