From “Printemps qui Commence“ (spring is beginning) to “Springtime for Hitler"... that really is quite some intellectual leap. Patrick Mason, an experienced and respected opera director, has uprooted the tale of Saint-Saëns's opera from biblical Gaza, and has placed the first two acts in France somewhere around the time of Jean Renoir's La Grande Illusion, with Warsaw ghetto overtones.

It’s well-known that Wagner shelved The Ring two thirds of the way through in favour of Tristan with the aim of producing something that could be put on quickly in a conventional theatre. Of course, it didn’t quite work out that way. Yet Tristan, for all its technical difficulties, does lend itself to a relatively small stage. Its ensemble scenes are few and manageable, and for the rest it’s basically a conversation piece.

What a difference seven years can make to a budding genius. Mozart’s La finta giardiniera (1775) has only patches of brilliance, and last year’s Glyndebourne production, despite musical excellence, failed them all.

2013 was the year that pop fans were forced to ponder the ethics of “Blurred Lines”. In 2014 classical fans followed suit, when Kasper Holten’s Royal Opera Don Giovanni unapologetically redrew the map of sexual boundaries. Suddenly Donna Anna was sneaking off for a quickie with the Don while her beloved laboriously declaimed “Dalla sua pace” – a willing partner (along with Elvira, Zerlina and all other women to hand) rather than a victim. Now Holten’s Don returns, if not precisely a reformed character, then at least a changed one.

Connections are missed and made in Jonathan Dove’s Flight – a giddy airport fantasy of what might be and what never was. Not yet 20 years old, this contemporary score is quite a departure from Opera Holland Park’s staple fare of well-aged verismo and bloodily rare Italian drama, but in a glossy new production by Stephen Barlow it pulses with all the same urgency and human interest – and not a suicide/secret pregnancy/long-lost parent in sight.

Of the two works by Hans Werner Henze on this curious if ultimately satisfying double-bill, neither quite answers to the name of opera. Henze originally conceived The Country Doctor as a radio opera, that still-rare and unfairly maligned genre, which allowed him to set the whole text as Kafka wrote it, with the doctor a disembodied voice at front and centre, a neutral observer of his own mental disintegration while the imagined events of his long dark night of the soul work their horror around him.

In a curious deal, two operatic card games were running almost simultaneously last night. At the London Coliseum, Tchaikovsky’s outsider Hermann was gambling for his life on three hands of Faro in The Queen of Spades, while in home counties countryside, Robert Storch aka Richard Strauss thought he was relaxing from a performance with a nice game of Skat when in comes a telegram from his tricky spouse Christine, aka Pauline Strauss, unsigned as usual, accusing him of adultery.

The delicacy of its supernatural elements make Pushkin’s The Queen of Spades, as adapted by Tchaikovsky, a tricky proposition for any director. Do you go with the ghost story and risk losing your audience emotionally, or do you play it straight, trying to rationalise the plot’s moments of macabre? The hands of the clock stand perpetually arrested just moments before midnight in David Alden’s new production for ENO, putting his audience out of any doubt as to which he has chosen.

Many matches are made in Fiddler on the Roof but the matchmaking prize goes to Grange Park Opera for getting Bryn Terfel to take on the role of Tevye. Having only recently played Sweeney Todd, and indeed throughout a varied career, Terfel has proved that he can treat lighter music with respect and sincerity, not to mention plenty of good humour.

Debussy completed only one opera (though he started plenty), but it’s the most perfect work imaginable, not only in sheer musical refinement and narrative precision, but in psychological penetration and above all in that exact grasp of the irrational nature of the medium that distinguishes the greatest operas from the merely effective.