'Unreleased’, proclaims the minimalist cover of this Bartoli album from November 2013. Why the wait? In the booklet Bartoli explains that these ‘long-lost friends’ came to light, serendipitously, as she was rummaging through her sound archives during lockdown. Given that the mezzo is one of Decca’s best-selling classical artists, it’s mighty odd that these Swiss recordings have been held back for over eight years. Perhaps Bartoli herself was originally dissatisfied, and has now relented?

If she was unhappy with these scenas spanning the last three decades of the 18th century, it’s hard to see why. By 2013 Bartoli’s middle register had grown darker and more opaque. But her dramatic flair, her unerring gift of locating the music’s nerve ends, are as vivid as ever. Coaching his first love, Aloysia Weber, in ‘Ah, lo previdi!’, Mozart urged her to ‘think carefully about the meaning and force of the words – to put yourself completely in Andromeda’s situation – and to imagine yourself to be her!’ That crisply sums up Bartoli’s approach to these Classical heroines and (occasionally) heroes in extremis, each of whom emerges as a vital, distinct individual. Nothing she does is ever blandly generic.

Native Italians always have an inbuilt advantage in this repertoire, though few use their own language with such detailed expressiveness. From the venomous rolled ‘r’ at the opening of Beethoven’s ‘Ah! perfido’, Bartoli declaims and colours the recitatives with the power of a great tragic actress. True to form, she never holds back. In ‘Ah, lo previdi!’ – arguably Mozart’s first vocal masterpiece – she burns into the opening aria with shocking ferocity. Bartoli does indeed ‘become’ the desperate Andromeda, grieving for her dying husband and longing for her own death.

After the mingled panic and intense pathos of ‘Ah! perfido’, Bartoli finds softer, warmer colours for the opening of Idamante’s ‘Non temer, amato bene’, written for a Viennese revival of Idomeneo. Here and in the favourite ‘L’amerò’ from Il re pastore, sung with yearning tenderness, Maxim Vengerov, no less, duets suavely with the voice. It is hardly his fault that the violin’s graceful frolicking in the second part of Idamante’s scena goes right against the sense of the words. Hurling out imprecations at the ‘pitiless stars’, Bartoli more than makes amends.

Bartoli brings a grieving inwardness to the one rarity here, a lyrical aria for the lovelorn, vacillating Sesto from Mysliveček‘s La clemenza di Tito, written nearly 20 years before Mozart’s. In Bella mia fiamma she uses the tortuous chromaticism – apparently written tongue-in-cheek by Mozart to challenge the soprano Josepha Duschek – to enhance the character’s disturbed state of mind. In the Allegro, taken at a ferocious tempo, Bartoli unfurls her familiar piledriver coloratura. Some, including me, will find this grating. Others may feel it creates an almost unhinged climax to a performance of expressionist extremes – a description equally applicable to Bartoli’s volatile, unflinching Scena di Berenice.

All the while the Basel players under Muhai Tang (including a fortepiano continuo that delicately enhances rather than irritates) are prompt accompanists, though they are rather short-changed in the balance. Haydn’s subtle woodwind colours in the Scena di Berenice sound distinctly muted here. Bartoli’s legion admirers will of course need no prompting. And after laying into Decca’s glossily vacuous presentation in her two most recent albums, I can happily report that we get full texts and translations plus a detailed, well-translated essay from Markus Wyler that sets each number in context.