Opera Rara celebrated Bastille Day with a tribute to two great French singers, Julie Dorus-Gras and Gilbert Duprez. Dorus-Gras was a leading soprano in Paris in the 1830s and 1840s, creating key roles in operas by Meyerbeer, Halévy and Berlioz. Duprez changed the course of tenor history, famed for being the first such singer to employ powerful chest voice for top Cs in Rossini's Guillaume Tell. Stepping into their shoes at Cadogan Hall were two singers with remarkably individual voices, Joyce El-Khoury and Michael Spyres, for a toothsome programme of arias and duets.

In the 1828, Duprez left Paris for Italy, working with Donizetti, developing – and retraining – his voice until his triumphant return to the Opéra in the 1830s. Spyres too has gone through vocal retraining, making the shift from baritone to tenor. The result in an astonishing voice which moves from an incredibly dark lower register to a gleaming top, into which he throws outrageous high notes immediately prompting thoughts which usually only find their way into print using asterisks! “Ils s'éloignent! je reste” from Daniel Auber's Le Lac des fées was a perfect example. Albert finds an enchanted lake where swans transform into fairies (stop sniggering) and falls for Zéïla. His gentle aria, in which Spyres maintained a classy bel canto line, then became agitated as Albert hears the fairies approaching, the final section erupting in what sounded like an interpolated high F natural. Spyres remained tireless, even when a role's tessitura was pitched impossibly high. Rossini's Otello and Halévy's Guido (Guido et Ginévra) gave us all the thrills without the spills.

Joyce El-Khoury's soprano is distinctive – dark plum notes at the bottom, supple phrasing and a bright upper timbre which can harden a little under pressure. Unfortunately, she was bravely battling the effects of a summer cold which hindered her usual ability to spin soft notes, such as the veiled opening to Isabelle's aria from Robert le diable. But when her voice opened out, there was power and commanding technique. The vocal colours El-Khoury drew in “Regnava nel silenzio” from Lucia di Lammermoor (one of Dorus-Gras' most prominent roles, including a successful run of performances in London in 1847-48) showed great dramatic instincts, demonstrating that Lucia does not always have to be sung by canary-light coloratura sopranos.

Duprez created the role of Edgardo and often sang opposite Dorus-Gras, so we were treated to the Act 1 duet in which Spyres and El-Khoury drew sparks from each other. The programme's most ear-opening number was the extended duet from Guido et Ginévra in which the demands Halévy makes on the singers are immense, the tenor especially, whose tessitura is set ridiculously high. Both singers responded with zeal, Spyres pinging out top Ds with apparent ease. Their encore was the Act 4 duet from Les Martyrs (premiered by Duprez and Dorus-Gras in 1840), recreating an earlier Opera Rara triumph the other side of the Thames back in 2014.

If there are going to be acres of orchestral filler in an operatic programme, I can't think of a better combination than the Hallé and conductor Carlo Rizzi. Continuing the theme of rare French opera, Auber's overture to Manon Lescaut fizzed, while there was full-blooded weight behind the overture to La Favorite. The chosen ballet music – also from La Favorite as well as Verdi's Jérusalem – didn't really show either composer at their most inspired, though were both played with verve. The real orchestral delights came in solo cameos in the arias: leader Simon Blendis floating ethereally in the entr'acte to Isabelle's air from Le Pré aux clercs; and fabulous trumpet solos from Gareth Small in Spyres' Halévy aria and again in the Favorite ballet.

Rare repertoire, polished orchestral playing, thrilling singing – it's no wonder London's operatic cognoscenti were out in force. They were amply rewarded.