"Ascanio is never staged here, and seemed well worth exploring," says Lang, the festival's artistic director. "It tells of the betrothal of Aeneas's son Ascanius to the nymph Rhea Silvia, and needs a really imaginative handling. I think Stephen Lawless has solved it brilliantly. Mozart's music is enchanting, and with Harry Christophers at the helm, it is in ideal hands." The countertenor William Purefoy sings the title role; the cast includes Gillian Keith and Tom Randle.
Why Nicolai? "It's a wonderful opera," says Lang. "The music is fabulous, and it's scarcely ever mounted professionally over here. Nicolai was German, but the opera feels much more Italian.
"It's a perfect Buxton piece - lithe, witty, fast-moving. There are several beautifully written arias, and a saucy forest trio for Falstaff and the two ladies; sheer delight."
The baritone James Rutherford stars as the hapless knight, as part of a strong cast.
Buxton has also commissioned a children's opera, The Hollow Hill by Ian McQueen, which centres on youngsters staging A Midsummer Night's Dream and being led into a magic cavern, where they have their own "dream" experience.
"It's clear our audience is keen to encounter new and different things," says Lang. "We have almost 120 events over 17 days [on the literary side, P D James, Harold Pinter and Robert Harris rub shoulders with Andrew Marr and William Hague]. We have tried to give people as wide-ranging an experience as possible."
8 to 24 July (0845 127 2190; www.buxton-opera.co.uk)