“A titanic composition by the standards of any period of musical history,” proclaims Bertil van Boer in his informative booklet-note, and with good reason. Clocking in at nearly six hours – Wagner eat your heart out – Kraus’s six-act (including a Prologue and lavish ballet sequences) ornamented Virgilian epic Aeneas i Cartago is surely the 18th century’s longest opera. Plans to perform it at the inauguration of Gustavus III’s new Stockholm Opera House in 1782 were stymied by factional intrigue and the hasty departure of the prima donna to escape her creditors. After further delays the opera was finally premiered, in a drastically truncated form, in 1799. By then, though, Kraus had been dead seven years.

Although scenes from Aeneas have been given at Drottningholm and elsewhere, its monumental scale has ensured that it has yet to be staged, or recorded, complete. Venturing yet again into uncharted territory, Naxos here offers a taster of Kraus’s magnum opus with 70 minutes of overtures, marches and ballet music. Churlish though it might sound, I wish they had included a smattering of solos and choruses amid the instrumental numbers. Still, there is some splendid and stirring music here, above all in the two overtures and the magnificent extended closing Chaconne, which for power and inventiveness surely rivals that to Mozart’s exactly contemporary Idomeneo. Gluck, who allegedly praised Kraus’s “noble style” after studying the overture to the Prologue, is a prime influence, though Kraus has a beguiling melodic vein of his own. One or two dances can seem too decorous for the context: huntsmen, for instance, disport themselves to the strains of a dainty minuet, while an archery contest unfolds to the blithest of gavottes. A few other numbers – say, the Introduction to Act 5, all agitated gesture over static harmonies – cry out for stage action to make their full effect. But Kraus is at his most vivid in the gracefully undulating Dance of the Naiads, a swashbuckling March of the Numidians, complete with raucous “Turkish” percussion, and a pair of dulcet minuets before the final Chaconne.

Performances, if not outstanding, are more than acceptable. Several tempi, both in fast and slower numbers, seem on the leisurely side. Period instruments would certainly have made for lighter, springier articulation, as in the Overture to Act 1, where repeated bass-lines tend to chug rather than dart and quiver. But Patrick Gallois evidently relishes the music’s colour and melodic charm, and elicits shapely, graceful phrasing from his Finnish players. While it would be quixotic to expect a complete Aeneas, I hope Naxos may soon net what is perhaps Kraus’s masterpiece, the moving Begravningskantata composed for the funeral of Gustavus III.