Grand and uncommon, Handel called the libretto for his oratorio Belshazzar - and his words perfectly described Saturday's Prom performance by the Orchestra and Choir of the Age of Enlightenment, conducted by England's vintage Handelian, Sir Charles Mackerras. There are choruses for three warring nations, a line-up of extraordinarily moving characters - and, of course, the spooky writing on the wall, here declaimed in some of the most chilling accompanied recitative yet written. Mackerras and his forces easily persuaded us that this is one of Handel's underperformed masterworks. As strongly and sensitively paced as the musical drama itself, the robustly yet sensitively inflected playing of the OAE found out every secret of Handel's heart. And the choir, whether as blustering Babylonians, urbane Persians or sober, unaccompanied Jews, gave lithe muscle to every ringing word.

There were two fascinatingly contrasted counter-tenors on hand, too: Iestyn Davies to provide a noble legato of faith for Daniel, sealed by subtle vocal ornamentation; and Bejun Mehta, sending electric currents coursing through the music of Cyrus, the conquering hero. Unlike Belshazzar himself, who, in the tenor Paul Groves, was disappointingly unstylish, Mehta and the superb Rosemary Joshua as Belshazzar's mother, Nitocris, charged the inner energies of Handel's writing with thrillingly intense musical intelligence.

Sunday's concert offered another choral masterpiece, Beethoven's Mass in C, sympathetically performed by the BBC Singers and the City of London Sinfonia conducted by Richard Hickox. Beethoven and Mozart (Symphony No34) framed Nigel Osborne's Flute Concerto, a work of strange and special beauty, with every elusive sound from its small orchestra perfectly distilled, it seemed, from the quintessence of the flute's own character. Sharon Bezaly caught its trembling, trilling evanescence at the heart of what would have been a perfectly proportioned concert without the otiose presence of Vaughan Williams's Song of Solomon-inspired suite Flos campi, a meandering and maudlin 20 minutes' worth of English orientalism.

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