Just when you thought Christmas was well and truly over, along comes another box of delights. And there isn’t a disappointment in it. If it were nuts, there’d be nothing but cashews; if chocolates, there wouldn’t be a single disgusting lime-cream. It would be all Ferrero Rochers, gift-wrapped. English National Ballet’s 70th birthday party opened and closed with class, in every sense.

It’s unlikely that Lord Byron would recognise much about Le Corsaire. Beyond the characters’ names and the Ottoman location, there is little trace of the 1814 bestselling verse-novel on whose fame the ballet hitched a ride. Its plot is very silly indeed – a tale of abducted slave girls and piratical derring-do with added 19th-century ballet tropes of poisoned flowers and opium-induced dreams, not to mention a shipwreck in the final three minutes.

A pas de deux is normally an opportunity for two dancers to express the pinnacle of their skill and the choreographer's art. In the case of McGregor + Mugler, the duet receiving its world premiere as part of a Russian-sponsored triple bill, it became an opportunity for a big-name designer to strut his stuff.

What price a pair of seats at the ballet? If you’re talking the latest starry Russian import then, with a few perks thrown in, you might not see much change from £800. And yet the size of the first-night crowd queuing for Modanse, a double bill starring the Bolshoi prima Svetlana Zakharova and a bunch of her pals, apparently required the erection of crush barriers along St Martin’s Lane.

Like almost everything that it touches these days, English National Opera’s autumn season of shows rooted in the Orpheus myth has enjoyed a fairly mixed reception. The company’s programme of visits to the Underworld concludes with another high-risk journey: Philip Glass’s 1993 opera Orphée, inspired by the 1950 film that Jean Cocteau spun from his own earlier drama on this theme.

Advance publicity overstated the case for The Mask of Orpheus. "Iconic"? Only to academics and acolytes, for British audiences haven't had a chance to see a production since ENO's world premiere run in 1986. "Masterpiece"? Sitting there after the second interval 33 years ago, surrounded by empty seats long vacated (by fellow critics, shame on them, among others), and facing a third act with a sense of fatigue, I hardly thought so then.

Maybe some British opera houses just don’t get operetta. Without wit, lightness and snappy pace, cudgelling us with desperate relevance, the frothiest works crash to earth stone cold dead. There have been disasters elsewhere, too, though ENO is the chief culprit, and (after a miserable Merry Widow and a fearful Fledermaus) this one is the nail in the coffenbach. If you think that’s a bad joke, wait til you hear the ones on stage.

English National Opera chose a curiously low-key production to open their season. Gluck’s Orpheus and Eurydice has only three singing roles and very little action. For this production, Wayne McGregor has reimagined the work as an opera/dance hybrid.

This well-meaning biographical jukebox musical about icons Gloria and Emilio Estefan, which did two years on Broadway and a US tour, is good summer scheduling, what with its Latin-pop bangers, infectious dance routines and “Dreams come true” messaging.

English National Opera continues its run of semi-staged musicals, in commercial collaboration with Grade Linnit, with a revival of this vintage oddity. Mind, commercial might be a stretch, as Dale Wasserman, Joe Darion and Mitch Leigh's 1965 work – it quickly transpires – is a tough sell, particularly in a quixotically cast revival that struggles to find a coherent tone.