In tribute to the late Shirley Verrett, I grabbed a Decca DVD of a famous 1976 Tosca from the Met that had found its way onto my desk (actually someone else’s desk, but when I saw the cast – Verrett, Pavarotti and Cornell MacNeill, in a Tito Gobbi production, I swiped it) and eagerly loaded it into my player. I’ll leave a judgment on the performance for another time. But I simply must comment on the extra features.

Too many opera and concert DVDs, especially archive ones, don’t bother with any such bells and whistles. I understand why – they’re quite pricey to produce and producers reason that the natural audience for these things won’t be able to live without them in any case, so in these straitened times it’s a needless expense. But in this case the extras are quite wonderful, almost worth the price of the set alone.

To start with, you get a very nice bit of rehearsal footage with Verrett and Pavarotti around a piano with the conductor James Conlon. It’s fun, and revealing in as much as it shows the detail that these artists actually did pay to phrasing and so on (there is sometimes a school of thought that Pavarotti in particular just opened his mouth and out it poured).

Then come the real goodies. A marvelous discussion between Scarpias past and (the then) present, Gobbi and MacNeill. Gobbi, most complete of all Scarpias, is surprisingly shy but witty and perceptive nonetheless; for him, Scarpia’s prime motivation is the fact that if he doesn’t catch the fugitive Angelotti he’ll be taking the prisoner’s place at the gallows. There’s also a great anecdote about a malfunctioning knife.

If Gobbi was a veteran by that stage, his Scarpia was in his prime and very experienced. Which is more than can be said for his (excellent) conductor. The final gem here is an absolute hoot – and I mean that in the nicest possible way. James Conlon, all of 26, is interviewed by the Met’s James Levine, a baby-faced 35 year-old. As the two of them chat animatedly and eagerly around the piano, it’s feels almost like some kind of post-grad music club rather than the thoughts of two Leading Conductors! The energy and enthusiasm, the sheer joy in music, that these two must have brought to the old place back then must have fired up all those working on the production. Who says that this fad for thrusting young conductors is a new thing? And, I wonder, will the likes of Yannick Nézet-Séguin, Gustavo Dudamel and the rest have a similar effect on US musical life to these now-eminent forebears?