You can’t have Viennese operetta without gold braid, frogging and moustachioed cavalry officers, and Kálmán’s ‘military operetta’ Ein Herbstmanöver is in a soldiering tradition that embraces Suppé’s Light Cavalry and Oscar Straus’s The Chocolate Soldier. Putting the Habsburg army on stage was as obvious a move for Austro-Hungarian composers as it was for Gilbert & Sullivan to climb aboard HMS Pinafore, and in fact Ein Herbstmanöver (Tatárjárás in Budapest and The Gay Hussars on Broadway) was Kálmán’s very first operetta. Its success prompted him to move to Vienna.

But make no mistake, it’s fresh off the puszta. A regiment of Hussars on autumn manoeuvres is camping on the country estate of the recently widowed Baroness Riza. But her old flame Lörenthy is on the staff: entanglements, both romantic and military, ensue, and Kálmán’s score glows with Hungarian colour, fizzy comedy numbers and long-breathed, bittersweet waltzes. From the fiery overture to the sudden arrival of a gypsy band, it’s easy to see why Vienna should have been swept away by such a fresh and colourful new voice.

Amid a spate of recent Kálmán releases, this is a clear winner. It’s taken from a 2018 staging in Giessen, and the producers re examined the original 1908 performance material before making a few changes of their own. The trouser role of Marosi is taken by a tenor (Clemens Kerschbaumer), two numbers from another show have been inserted and other items have been re-ordered and cut. The spoken dialogue has largely been omitted. Still, demanding textual purity in operetta is like seeking an ‘authentic’ recipe for goulash: rather beside the point. What matters is how good it tastes.

And as long as you’re not in the market for Staatsoper opulence, this tastes great. Christiane Boesiger as Riza has enough vocal richness to be seductive (with just a hint of sour cream); as Lörenthy, Grga Peroš has a sunny, matinee-idol baritone. They’re a charming pair and they’re both at their best in their half-melancholy, half-rapturous near-duets, floating the ends of phrases and uncoiling the long finale to Act 1 with tenderness and poise. Kerschbaumer is a lively light tenor, Marie Seidler makes a sparky Treszka and Tomi Wendt is a lot more musical than he needs to be in the comedy role of Cadet Wallerstein.

If anyone deserves to be mentioned in dispatches, though, it’s the conductor, Michael Hofstetter, who launches the Overture with moustache-twirling élan and has an unerring sense – as vital to Kálmán as a Viennese lilt is to Strauss – for the precise moment when a csárdás starts, imperceptibly, to accelerate. His panache is matched by his sensitivity in the slower numbers: for an escapist comedy, Ein Herbstmanöver is surprisingly poignant, and I found the mixture captivating. So it pains me to say that the glossy booklet contains no libretto and a worse-than-useless synopsis. Still, Kálmán’s score is so piquant and these performances are so zestful and affectionate that I urge you to enjoy it regardless.