There is only one rule by which one should ever judge a Barber of Seville. If your eyes (and possibly also your trouser legs) aren’t moist by the time the interval arrives, you might as well leave. The last time this Jonathan Miller production was revived by the English National Opera, it passed with flying colours. This time round, I was dry as a bone. Three hours and I notched up two smiles and a snigger.

Janáček’s opera subjects – the 300-year-old opera singer, the composer with a mad mother-in-law, the Siberian prison camp – are by any standards a fairly rum collection. But The Cunning Little Vixen is arguably the most deviant of the whole bunch. Its foxy heroine (out of a Prague newspaper cartoon strip) is captured by the local Forester, lectures his hens about their subservience to the Cockerel, slaughters the lot of them, runs off, marries, starts a family, then allows herself to be shot by the poacher. All very charming, random and pathetic, one might feel.

How do you solve a problem like Medea? Euripides’ baby-killing, hell-invoking sorceress is one of literature’s most terrifying and unfathomable creations – a woman capable of murdering her own children just to watch their father’s pain. Yet with the blood on her hands now centuries-old, Medea continues to work her grim enchantments on artists. No fewer than eight operas (and an almost equal number of plays) have staged her story, but have any really got to grips with the psychology of tragedy’s wickedest witch?

Last week Lulu, this week Cio-Cio San, next week the Vixen Bystrouška. These are the three exemplars of David Pountney’s “Free Spirits” – as he labels his first themed season with WNO. But it’s hard to see poor little Butterfly, pinned to a board by the cruel American sailor-lepidopterist, as a free anything. Like a trapped fly, Suzuki calls her; and if there’s a free spirit in Puccini’s opera, it might rather be Pinkerton himself, “dropping anchor at random,” as he boasts to Sharpless: not such an inspiring thought.

“All we do is talk!” complains the unnamed protagonist in Poulenc’s brilliantly concise one-act opera La Voix Humaine, a faithful setting from late on in the composer’s career of Cocteau’s 1930 play. Banter is what you don’t get; the heroine’s dialogue with her former lover is conducted via an unreliable landline. The audience hears only one side of the conversation. It’s a chilling, emotionally charged piece – though the latent naturalism is slightly undercut by the unseen presence of a full orchestra underscoring every move.

Since I last reviewed Opera’r Ddraig (no longer offered as Dragon Opera in their publicity) two years ago, this company of students and postgraduates has moved house, and this year is staging its main show, Offenbach’s delightfully absurd Orpheus spoof, in the cavernous old Coal Exchange down by Cardiff Bay.

The “Mastersingers of Manchester”, about 350 of them, were gathered together by Sir Mark Elder to celebrate the Wagner bicentenary with this performance of Act Three of Die Meistersinger von Nürnberg in its entirety. He also pulled in about 200 orchestral musicians, exploiting the city’s resources just about to the limit.

The Barbican is London’s home for baroque opera in concert, regularly bringing Europe’s finest over with their latest Handel and Vivaldi. But although fresh from a performance in Paris, last night’s band were definitely home-grown. Harry Bicket and the English Concert were joined by a dream-team of soloists for a performance of Handel’s Radamisto that suggested their French rivals aren’t going to have it all their own way this season.

What-ifs and might-have-beens are usually as pointless in music as in any other walk of life. Still one can’t help wondering how Alban Berg would have completed – and, no less interesting, revised – his opera Lulu, if he hadn’t been stung by some philistine insect in the summer of 1935 and died of the resulting septicaemia that Christmas Eve, with the last act unfinished and barely half-orchestrated.

It may look like a sure-fire hit to let Kansas mezzo Joyce DiDonato rip through the drama-queen repertoire of the Baroque. But last night’s exploration of the dustiest, most overgrown byways of 17^th and 18^th century Italian opera needed every drop of DiDonato’s star musical talents – not to mention those of her backing band Il Complesso Barocco – to convince us of the worth of these rarities. The audience bought it. I remain on the fence.