Senesino (nickname for Francesco Bernardi) set the template for the star castrato with attitude. In contrast to the far more amenable Farinelli, he was evidently a colleague from hell: preening, hot-tempered, likely to throw a tantrum at the slightest provocation. His outrageous behaviour made him a satirist’s gift. Yet in his prime between around 1710 and 1735, ‘the Sienese’ enchanted audiences in London and Italy with the mingled power, sweetness and agility of his singing. He was, with soprano Francesca Cuzzoni, the prime draw in Handel’s operas of the 1720s, most famously as Giulio Cesare.

In his tribute to one of the greatest singers of the age, American countertenor Randall Scotting reminds us that Senesino honed his reputation not in Handel but in obscure operas by Italians whose works have faded from view. All but one of the arias here are recorded for the first time. Of the composers on display, Lotti, Bononcini and perhaps the Florentine Giuseppe Orlandini will be familiar names to most Baroque lovers. The monk turned composer Attilio Ariosti was, with Bononcini and Handel, one of the ‘renowned triumvirate’ (Charles Burney’s words) associated with London’s Royal Academy in the 1720s. But I confess I’d never until now heard of the once-famous Turin-born Giovanni Giaj, or the obscure Bolognese Giovanni Ristori.

Senesino’s speciality was kings and emperors (hence the album’s vote-catching title) in roles that combined heroism and vulnerability. While he excelled both in pathos and in fiery coloratura – what the 18th century dubbed ‘long divisions’ – most of the arias chosen here are reflective. Scotting’s full, darkly mellifluous voice – smooth and even throughout its range, with a resonant lower register – is well suited to these elegies, meditations and amorous outpourings. Scotting duly takes note of Senesino’s famed ‘taste’ in ornamentation – here mainly restrained – and shapes each aria with a feeling for the character’s predicament. Animated by Laurence Cummings’s lively figured bass realisations, the OAE play with their familiar style and finesse.

Scotting unfurls his coloratura prowess in a ‘vengeance’ aria from Giaj’s Eumene, complete with baying horns, and powerfully conveys Megacle’s conflicted, fluctuating emotions in an aria from Orlandini’s Olimpiade. He is dulcet, tender, in two charming numbers by Bononcini (who writes the album’s best tunes) and in a pastoral aria by Lotti. For all Scotting’s vocal refinement, some of the arias trip along too inconsequentially for their dramatic situation, none more so than a dull solo from Orlandini’s Adelaide. A more animated tempo might have helped here. Beyond this, the programme would have benefited from a couple more bravura items to show off the ‘fire in Allegros’ for which Senesino was admired. Moderato sameishness is not quite avoided. Still, the offbeat repertoire is rarely less than agreeable, the performances eloquent, and Signum’s documentation a model of what these things should be, with essays by Michael Burden and Scotting himself and a note on each item that sets it clearly in context.