Send in the clowns, as they sing in this palace-of-varieties first act, not for Pagliacci, Leoncavallo’s sole foothold on today’s operatic repertoire, but for the fool-for-love heroine of a sparkling, swooning rarity. Musically, Zazà is a notch above Mascagni and Giordano for orchestral delights, just below supreme genius Puccini, but its admittedly thinly-spread plot ends by being rather remarkable.

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.

Alice Coote (b.1968) is one of the world’s leading mezzo-sopranos. She grew up in Cheshire, born to two painters, Mark Coote and Mary Moss, and learned her craft at the Guildhall School of Music and Drama, the Royal Northern College of Music and the National Opera Studio. Her breakthrough came in 2000 when, within the time frame of a fortnight, she sang Ruggiero in Handel’s Alcina at the Edinburgh Festival, and Poppea in Monteverdi’s The Coronation of Poppea at the ENO.

At the end of last night’s giddy, triumphant concert at the Barbican, Joyce DiDonato was presented with a bouquet by a member of the audience. It included, among more conventional flowers, a tomato plant, complete with ripe tomato. That says it all really. Just imagine Netrebko, Gheorghiu or even Bartoli faced with a tomato and the confusion that would ensue.

The mezzo-soprano Brigitte Fassbaender, who will be 75 on Thursday 3 July, was unsurpassed for dramatic impact and presence in roles such as Octavian in Der Rosenkavalier and Prince Orlofsky in Die Fledermaus, during a singing career which spanned from the early 1960s to the mid-1990s.

Her command of the long lines of Mahler's songs, and the immediacy and understanding she brought to Lieder generally placed her in the very top flight of interpreters alongside Dietrich Fischer-Dieskau, Peter Schreier and Christa Ludwig.

It's the genre of gender-bending and cross-dressing, where women play warriors and men sing like women (while playing warriors). But when it comes to opera, who really wears the trousers? For at least 300 years the answer has been pretty definitive. Women have donned breeches and boots to play opera's many "trouser roles" in music from Handel and Mozart to Massenet and Offenbach.

There’s nowt so French as the mélodie and the chanson, but I’m not convinced they make ideal bedfellows. Nor, I suspect, is Anne Sofie von Otter, since she split the salon and cabaret halves of her Douce France recital with an interval (and the CD release of the same name with a change of disc). The art song and the popular tune may spring from the same national sensibility but they have little in common: the one is subtle and born of poetry, the other musically primitive and emotionally blatant.

She’s the Kansas mezzo-soprano whose ruby slippers have now taken her across the globe, singing in all the great opera houses, but who has never lost the common touch. She’s not a diva, she’s a “Yankee Diva” – a contemporary creature who would never dream of throwing a tantrum or cancelling at short notice. She's Joyce DiDonato.

What’s the perfect Glyndebourne opera? Mozart, of course, must have first and second places with Le nozze di Figaro – Michael Grandage’s lively production of country-house mayhem is revived again this season – and Così fan tutte. Then comes Amadeus’s greatest admirer, Richard Strauss, and Ariadne auf Naxos - his most experimental collaboration with his then-established house poet for Elektra and Der Rosenkavalier, Hugo von Hofmannsthal.