When composing Tamerlano, Handel himself made significant changes to the libretto, enlarging the role of Bajazet to showcase the talents of his new star tenor import Borosini, while keeping the good-guy-heartthrob role of Prince Andronico for his famous castrato Senesino (who refused ever to play villains, in case it might put off his swooning fanbase). Understanding these dynamics is key to enjoying Tamerlano today: part of Handel’s skill was not only creating fabulous music, but manipulating the proud egos of his principals with supreme effectiveness. Il Pomo d’Oro’s Tamerlano became, fittingly, a duel of musical excellence between John Mark Ainsley’s brooding, noble Bajazet and Max Emanuel Cenčić’s sweet-toned, charming Andronico, with character-rich portrayals from lesser characters giving them something to fight over for the next three and a half hours of glorious music.

Baroque opera performances at the Barbican seem to be falling into a pattern at the moment: a concert performance from the stave, with singers standing demurely in black tie rather than costume (though Cenčić certainly stretched the envelope with a gold lamé evening jacket which he might have borrowed from Bruno Tonioli, and Lezhneva indulged in a diva-style interval change of dress, from hot pink to russet red). Devoid of props or scenery, and with the orchestra all over the stage, it’s a recognisably traditional format, but one that does take opera to the absolute brink of boring. Fortunately, Tamerlano finds Handel at his inventive, creative melodic best: just when you think you know where one aria is going, he unfurls the tune in a marvellous new direction, full of surprises and sudden gifts to singer and audience alike. So, if you’re ready to sit very still, and enjoy a lot of beautiful music, you’re in for a treat. But, with almost every aria applauded individually, and further ad hoc breaks for the orchestra to re-tune at least twice, it did begin to feel like forever, particularly when the subtitles misbehaved or gave up. The large audience remained serenely content, nevertheless.

Tamerlano may have been conceived as high tragic drama, but there’s a strong undercurrent of humorous parody, particularly to modern ears, in the vaunting yet largely unrealised threats of the warring emperors Bajazet and Tamerlano. Xavier Sabata played expertly on this atmosphere, his Tamerlano an unpredictably petulant tyrant with a definite dash of pantomime villain, tickling several chuckles from the audience. Deftly and expressively sung, Sabata’s Tamerlano can turn on a knife edge in his music, as well as his mood, moving with remarkable quickness and freshness through his array of notes, with slick timing inside a smooth legato. Cenčić gave a notably thoughtful, intense performance as Andronico: it felt as if he had been rehearsing this for months, every note perfectly judged, his portrayal expertly characterised. Andronico’s heartmelting music, one suspects, would have kept even the imperious Senesino happy, despite not being the title role: Andronico’s slow, melancholy “Bell’Asteria” sounds like it comes from another, better world. The dramatic heart of the evening was, quite rightly, John Mark Ainsley’s superb Bajazet, who aced aria after aria with supreme control. “Ciel e terra armi di sdegno” was a virtuoso vortex of notes, with huge surges in its register which Ainsley made seem effortless. His final death scene (delivered while standing) was also hugely moving.

Julia Lezhneva was not quite on her usual form as Asteria; off to an unsettled start, she flurried herself into her first aria, poise and tone both suffering. While we still had some ravishing sequences, and her signature eye-popping coloratura, her high notes sounded occasionally strained, the end of phrases often brassy. Recovering in her later arias, the delicacy of her ornamentation remained breathtaking when piano, but it was not until Asteria’s whirlwind “Non è più tempo” that Lezhneva really unleashed her bravura talents in a brilliantly sung, genuinely funny performance as the proud Ottoman princess defiantly telling her lover that he’s missed the boat.

Romina Basso took a stylish approach to Irene, a very scary princess who finally bends Tamerlano to her will, starting (one suspects) as she means to go on in marriage. Basso clearly relished her part, singing with fine tone and a keen sense of fun. Pavel Kudinov was also a treat in the smaller role of Leone, his rich bass making the most of his occasional appearances.

Maxim Emelyanychev conducts Il Pomo d’Oro in an engaging collegiate style, his flowing gestures almost a dance of shared intention: I found it increasingly absorbing to watch his graceful movements and pinpoint accuracy. Altogether, it was a magnificent evening of music-making, full of well-characterised singing: but the extended length, scale and punctured dramatic pace (thanks to so much applause) left it bereft of the psychological fireworks which might well blaze out from a full performance.