The trouble with Trovatore, Verdi’s sometimes barrel-organish, slightly middle-aged troubadour, isn’t so much the silly shocker of a plot, triggered by a gypsy so crazed with vengeance that she throws her own baby on a bonfire by mistake, as the choppy dramatic line, so hard to thread. Under the circumstance, Adele Thomas’s medieval-hell production could have been a lot worse, and the vocal quality is there throughout under Antonio Pappano’s watchful guidance.

Benoit Jacquot’s handsome period production of Werther has been quietly putting in the miles for the Royal Opera. Since its premiere in 2004, this unexceptionable staging – “this wall, this fountain, this cool shade” all present and laboriously correct – has supplied a London star vehicle for everyone from Joyce DiDonato and Isabel Leonard to Juan Diego Florez, Rollando Villazon and Vittorio Grigolo. Now it’s the turn of Jonas Kaufmann – or, at least, it was supposed to be.

Frederick Delius composed an opera called A Village Romeo and Juliet; Donizetti composed a sort of village Tristan and Isolde, but called it L’elisir d’amore – The Love Potion. The hero, Nemorino, inspired by the Tristan tale, buys an elixir off a passing quack, in the hope it will make the beautiful, capricious Adina fall for him.

Like any decent cake (and we saw plenty on the Holland Park stage), a tasty production of Hansel and Gretel needs a careful balance of flavours. Sweet and sharp; light and dark; fantasy and realism; fright and delight. Directed by John Wilkie, Opera Holland Park’s version of Engelbert Humperdinck’s well-preserved “fairy-tale opera” from 1893 skilfully mixes its ingredients into a sort of Great Grimm Bake-Off. It hints at horrors but never really threatens to turn sour.

Harrowing and holiness alternate in Poulenc’s unique masterpiece, nominally an opera about nuns during the French revolution, at a deeper level a music-drama about the greatest disturbances in the human condition. Glyndebourne’s cast, conductor and orchestra handle the variety wth total mastery. If Barrie Kosky’s production lets horror overwhelm us, that’s justified too. If you’re not a heap at the end of it, that’s your problem.

Sullivan’s score for his eighth collaboration with Gilbert is vintage work, mostly equal to the splendid sentinels flanking it, Iolanthe and The Mikado. On Wednesday night master animator John Wilson did its buoyancy and occasional pathos full justice. But what of Gilbert’s words? “A woman’s [sic] college! Maddest folly going!” doesn’t promise an operetta for our times.

“I am a poor student,” the Duke tells a smitten Gilda, in music that can barely keep a straight face, so plush is its melody, so oozing with confidence and privilege.

It’s a short step from there to Cecilia Stinton’s new Rigoletto for Opera Holland Park, which takes him – almost – at his word, transplanting Verdi’s rapey young aristo from 16^th-century Mantua to an Oxford college between the wars: a Bullingdon Club hooray to Rigoletto’s downtrodden college porter with a chest full of medals and a gammy leg.

Innovation is always a risky business. Opera North’s vision and ambition for this production is to create, in effect, a new genre: a combination of staged choral-orchestral performance with contemporary dance.

Partnership and diversity are the buzz words – good ones, too – and the concept brings together the opera company’s soloists, chorus and orchestra with dancers from both Leeds-based Phoenix Dance Theatre and South Africa’s Jazzart Dance Theatre, plus some help from Capetown Opera.

Götterdämmerung is not only the grandest of Wagner’s Ring operas, it is also the most varied. Siegfried’s journey down the Rhine transports him in a short quarter-hour from the hieratic world of the Norns and the World Ash to the soap-opera of the Gibichungs and their anxieties about marriage and political standing (opinion polls?).

Sometimes a production which isn’t trying to do anything too clever can be quite refreshing. Sinéad O’Neill's revival of Annabel Arden’s 2007 Glyndebourne touring production of Donizetti’s L’elisir d’amore is just that.