Cecilia Bartoli's unique talent has been delighting audiences for several decades, but she is an infrequent visitor to this country. Consequently, her concert at the Barbican with Rolando Villazón, part of a tour criss-crossing Europe, was something of an occasion. A murmur of discontent rippled through the Barbican Hall as the announcement was made that Villazón had been stricken by a cold, but had pledged to sing on nonetheless. I have rarely felt more sorry for a singer as he battled earnestly but unsuccessfully against a virus that clouded what used to be a pellucid voice and prevented high notes from being delivered with any beauty, or in most cases, success. How many of his vocal difficulties were due to his cold alone, I was unable to determine.

The duet from L'elisir d'amore, Una parola...Chiedi all'aura lusinghiera" demonstrated both Villazón's technical abilities – breath control, phrasing, plangent dramatic expression – and his vocal problems: declined versatility and difficulties in his high register. He seemed to return with renewed vigour after the interval for Bellini's song Torna, vezzosa Fillide, but he was defeated by the extended scene from Rossini's Otello, and consequently seemed to overact in compensation.

Bartoli's voice is patently not the fresh, crisp instrument it once was; her long career has started to dry its tone and her control slipped once or twice. That said, her famous staccato coloratura remains as powerful as ever, demonstrated in one of her signature pieces, "Nacqui all’affanno… Non più mesta" from Rossini's La Cenerentola, which she navigated with the utmost ease. Her perfect articulation and habitual colouring of every line with emotion and emphasis was on display throughout the concert. Bartoli's assumption of the role of Desdemona (featuring the apparently requisite change into an elaborate nightie) was the most interesting part of the evening. Largely obscured by Verdi's version, Rossini's is infamous for the alternative happy ending he inserted to please the censors in Rome. Bartoli and Villazón gave us a portion from the third act, essentially the last 25 minutes of Desdemona's life, in which she sings the Willow Song, prays and argues with Otello before he stabs her. Bartoli sang movingly enough. Her "Assisa a' piè d’un salice" was sung with a moving simplicity and was the highlight of the evening. Yet I was unconvinced by her portrayal of Desdemona, and on a more general point of repertoire, whilst Bartoli sang all her roles perfectly well, her voice is now simply too mature to convince as Angelina, Zerlina and Desdemona. She has recently taken on the role of Norma to critical success, and the role is a perfect fit for her current voice – if only she had given us something from roles such as that!

La Scintilla has been a regular collaborator with Bartoli for many years. Performing with period instruments and ably led by concertmaster Ada Pesch, they were very much a character ensemble, embodying the seductiveness of "Là ci darem la mano" as easily as the aching misery of "Assisa'". The strings in particular had a delightfully raw bite, which brought a different flavour running beneath the voices. Credit should be given to Una Prelle, whose harp solo in the Willow Song matched Bartoli in melancholy beauty, and the oboist Pier Luigi Fabretti, who performed Bellini's Oboe Concert with understated eloquence.

The evening ended with an encore of three duets, Rossini's La Danza, Lehár's "Lippen Schweigen" and the Brindisi from La traviata, in which Bartoli trilled and Villazón hammed it up, largely outshone by his partner but with an obvious dynamic between the pair. A summary of the evening in many ways, but not a bad way to begin the festive period.