Political machinations and backroom power-brokering, leadership battles and unscrupulous rivals – if ever there was an opera for this week it’s Simon Boccanegra. Premiered in 1857 but only coming into its own after substantial revisions in 1881, Verdi’s problem-child of a piece had its own struggle for survival and success, and the work’s rather lumpy dramatic architecture shows the scars of its various grafts and interventions.

Presenting the last Mozart symphonies as a three-act opera for orchestra, as Richard Tognetti and his febrile fellow Australians did on Monday, was always going to be a supreme challenge. It worked, as Boyd Tonkin reported here. Since then, the Barbican's grandiosely-named "International Associate Ensemble" has opened up the repertoire, synchronising with film (on Tuesday) and ending its mini-residency with the kind of vibrant rattlebag for which it's rightly celebrated.

Here it comes - get a grip. The tears have started flowing in the trio "Quid sum miser" and 12 minutes later, as the tenor embarks on his "Ingemisco" solo, you have to stop the shakes turning into noisy sobbing. The composer then lets you off the hook for a bit, but only transcendent beauty in singing and playing can achieve quite this effect in Verdi's Requiem.

Her special claim to fame was the most luminous pianissimo in the business, but that often went hand in velvet glove with fabulous breath control and a peerless sense of bel canto line. To know Maria de Montserrat Viviana Concepción Caballé i Folch, born in Barcelona 85 years ago, was clearly to love her. I never did (know her, that is), and I only saw her once, in a 1986 recital at the Edinburgh Festival. By then she was careful with her resources, but the subtly jewelled programme delivered on its own terms.

Everything is political in the world's current turbulent freefall. The aim of Riccardo Muti's "Roads of Friendship" series, taking the young players of his Luigi Cherubini Youth Orchestra to cities from Sarajevo in 1997 to Moscow in 2000 and Tehran last year, has simply been "to perform with musicians from different cultures and religions" in a community of peace.

Alzira is Verdi’s shortest opera and his least performed, and you have to ask why.

One wearies of quarrelling with opera directors’ concepts. But what’s the alternative? To ignore or acquiesce in crude, approximate reimaginings that, like Daisy Evans's new La Traviata at Longborough, stuff a work any old how into some snappy, after-dinner parody that says nothing useful about the piece, vulgarises the situations and confuses or misrepresents the text. 

All those pranks, set-ups, fake letters and disguises, they just keep coming thick and fast in Verdi’s Falstaff. The score has irresistible energy and momentum.

You don't have to be a good director to manage the artistic side of an opera house. Daniel Kramer arrived at ENO and boosted morale at a time when company relations with then-CEO Cressida Pollock had hit rock bottom, and his repertoire choices for the new limited seasons look fine so far.

You’d expect a degree of mischief and bafflement in an opera about mistaken identity, closing with a scene set at a masked ball. But Tim Albery’s new Opera North Un ballo in maschera is confusing for the wrong reasons, its shortcomings all the more irritating compared how good the performance actually sounds.