Fashion is a funny thing, in opera no less than the sartorial trappings that go with it (everything from tight, hipster trews to billowing ballgowns at last night's Glyndebourne season opening, in case you were wondering). Donizetti's classical tragedy Poliuto is historically a miss rather than a hit, never quite finding its footing in the repertoire, despite some early success.

Crotch-grabbing, suggestions of oral and anal sex, stylized punching and kicking and other casual violence offer diminishing returns in your standard Calixto Bieito production. Sometimes a scene or two flashes focused brilliance, which only makes you wonder why he doesn’t apply the same rigour throughout.

This was a very "concert" performance indeed. Across the stage music stands stood like sentinels lest any rash singer attempted to stand out and – surely not – act. Such fears were misplaced (or the stands did their job) in the end, as the music was what mattered and everyone stood and sang, with one outstanding exception, the Kundry of Mihoko Fujimura.

"The darkness deceived me," sings Leonora in Act I as she mistakenly rushes into the arms of the Count di Luna, rather than those of her beloved, the mysterious troubador Manrico who’s been serenading her for nights on end. Seeing Robert B Dickson’s sepulchral lighting in Scottish Opera’s semi-new production of Verdi’s melodramatic shocker Il trovatore – an updated version of the company’s 1992 staging – you can understand why.

I must have been one of the few in Saturday’s audience for Richard Ayres’s new opera who had never seen Barrie’s play or read the book, so I’m unable to judge how faithfully it renders the original – in case that matters. Somehow one knows the dramatis personae: Peter Pan himself, the Darling family, Nana the dog-nurse, Captain Hook, Tinkerbell, Tiger Lily and of course the ticking crocodile, who swallowed Hook’s watch along with his arm. They are all here, wittily, sometimes brilliantly, reimagined in Keith Warner’s panto-like staging.

Over the past decade Alice Coote has emerged as a singer of rare and exquisite vocal quality. Even when the direction of a project is questioned, there has generally been consensus that she generally sounds gorgeous. The concept of Being Both, a juxtaposition of Handel mezzo arias for both male and female characters, is brilliant both musically and commercially. It allows a fascinating exploration of identity and sexuality in a period when both, in opera, were pretty fluid; and it makes, conveniently, for a programme of Handel’s greatest hits.

When ENO announced its return to Gilbert and Sullivan, rapture at the news that Mike Leigh, genius Topsy-Turvy director, would be the master of wonderland ceremonies was modified by its choice, The Pirates of Penzance. Last staged at the Coliseum – and unmemorably – as recently as 2004, the fifth Savoy opera seemed less in need of revisiting than several larger-scale successors.

Jiří Bělohlávek and the BBC Symphony Orchestra are on to a good thing with Czech opera. Prague is a major centre for world-class opera, but much of the repertoire performed there is all but unknown abroad. Bělohlávek, who holds positions in both Prague and London, has found a way to broaden its audience: presenting a series of concert performances with the BBC Symphony Orchestra and soloists brought in from the State Opera. The repertoire may be obscure, at least for London audiences, but the idiomatic performances that result ensure nothing is treated as a mere curiosity.

How many words would you expect in an average libretto? 10,000? 15,000? Whatever that number is you can triple it and then some for The Virtues of Things – a new opera from Sally O’Reilly and Matt Rogers of astonishing, exhausting, battering wordiness. And with all these extra words what does it have to say? Not a great deal, frankly.

Let’s get one thing straight at the outset: Szymanowski’s 1926 opera Król Roger isn’t a lovely occasional oddity, a rarity whose appeal is largely novelty, or a dust-it-off-once-a-decade sort of piece. It’s that rarest of things, a real and original masterpiece whose worth has been unaccountably undervalued. This new production by Kasper Holten does nothing to obscure its beauty, making a strong case not only for the work’s sensual appeal, but also the larger philosophical architecture underpinning this maverick score.