Considering how rarely celebrated diva Cecilia Bartoli appears in London, Wigmore Hall certainly pulled off a coup by making her duo concert with star countertenor Philippe Jaroussky happen, albeit with a hefty price tag. As expected, the hall was packed to the rafters with a queue for returns, and the audience was not disappointed – they were thoroughly entertained by the artistry of this unique singer. For sure, her voice isn’t as supple or luscious compared to a decade ago (and her lower range is slightly coarse), but she still has the rare power to enchant the audience with her theatrical flair, ability to convey intense emotions, as well as her infectious sense of fun.

Their programme, entitled “Idolo mio” (after a love duet in Cavalli’s Elena), centred around relatively unknown arias and duets by Monteverdi, Cavalli and Steffani and interspersed with instrumental numbers. Probably most of the audience would only have been familiar with the Toccata and La Musica’s prologue from Monteverdi’s Orfeo and a couple of the canzonettas from his two sets of Scherzi musicali, but both Bartoli and Jaroussky are brilliant at bringing off this sort of obscure programme. Their presentation was quite theatrical, with the two singers coming on grandly through opposite doors of the Wigmore stage every time they sang, but the music was all performed seamlessly, flowing from one piece into the next organically without applause, that we didn’t feel at any point that the instrumental pieces were fillers. I especially loved the theorbo player’s improvised interlude between the arias.

It must have been a difficult programme to devise, because there isn’t really a lot of duet repertoire in Monteverdi, especially not for two similar mezzo-soprano range voices. Apart from “Zefiro torna” from Scherzi musicali (1632) which is scored for two voices, other numbers such as La Musica’s prologue from Orfeo and the vivacious “Damigella tutta bella” were slightly adapted, the two singers taking a stanza each and then duetting. The two operatic duets came from Cavalli’s opera Elena and Steffani’s Niobe (both Bartoli and Jaroussky have played a part in the revival of Steffani, Handel’s predecessor in Hanover), which made us yearn for more substantial duets. The most popular Baroque duet for two high voices, “Pur ti miro” from Poppea, was saved for the encore.

Elsewhere in the programme, Bartoli and Jaroussky entertained us alternately with their solo numbers. There wasn’t an over-arching theme in the programme, but some loosely themed groups of songs on love, lament, torment and battles. Often they would mirror each other’s sentiments, as in Alessandro’s lament from Cavalli’s Eliogabalo (Jaroussky) and Idraspe’s lament from Cavalli’s Erismene (Bartoli). In the former, Jaroussky touched the heart with his emotional intensity and focused tone. His two other Cavalli numbers (both from Xerxes) were also charming – a gently sung “Ombra mai fu” (composed decades before Handel) contrasting with the vocal fireworks in “La bellezza è un don fugace”. Bartoli sang impressively in Monteverdi’s Sì dolc’è il tormento, which featured some gorgeous solo contribution from the cornet player, although in general she seemed more at home singing Steffani than Monteverdi. “Amami e vederai” from Steffani’s Niobe was definitely a highlight: with just theorbo accompaniment, she sang in heart-achingly beautiful bel canto and had the audience captive, hanging on her every tone.

Ensemble Artaserse, a French-based ensemble founded by Jaroussky, was on excellent form. Each player would display solo virtuosity when required, but they could also be alert and flexible accompanists, especially the continuo players. I was awestruck by the versatility of some of the players – the two cornet players who brought several instruments on stage including recorders and would often change instruments within the piece, as well as the lirone player who doubled on the Baroque guitar. Leader Alessandro Tampieri charmed us in Pandolfi’s Sonata “La Biancuccia”. They were sonorous and achieved a good balance with the singers, and there was a convivial and lively dialogue between them all. In the final encore, Caccini’s catchy aria “Al fonte, al prato”, which was given a Spanish flavour with the percussionist playing the castanet, Bartoli and Jaroussky even started a little dance on stage!

It’s true neither has a large voice, and in that regard the Wigmore Hall is the ideal venue for both. In the hall, their voices blended better than I had thought, for although their vocal ranges are similar, they have a very different timbre. More than anything, I think the success of their duo is because they have a strong musical affinity for each other. They were very much equals on stage, and Jaroussky certainly had the artistry to match Bartoli.