Youth was everywhere to be seen at the Proms last night. Whether in the massed ranks of Britain’s National Youth Orchestra, soloist Ben Grosvenor (even younger than the precocious Benjamin Britten when he debuted his own Piano Concerto in 1938), Prokofiev’s Romeo and Juliet, or DJ-turned-composer Gabriel Prokofiev, it was an evening celebrating the scope of the teenage experience. Even the Late Night Prom joined in the party, coming courtesy of Nigel Kennedy, still surely the oldest and most defiant teenager in classical music.

It's not often that we in the critical world revisit a production towards the end of a run to see how it's settled. I had two reasons for wanting to return to Christopher Alden's English National Opera production of Britten's A Midsummer Night's Dream. First, I wanted to hear the liquid-gold countertenor of Iestyn Davies in action as Oberon, since he'd been voice-indisposed for one night only (and superbly doubled in that capacity by William Towers).

It’s the oldest coup de théâtre in the postmodernist playbook – the curtain rises to reveal an audience staring back at us – but still, in the opening seconds of Willy Decker’s Peter Grimes, one of the most effective. Our theatrical doubles here are sinister creatures indeed, massed rows of sombre Victorians whose brutal Christianity is no less severe than the angles of John Macfarlane’s set. As gazes meet across the courtroom in that moment we confront ourselves, discover ourselves in the folk of the Borough, implicated absolutely in their tragedy.

Just think, said a veteran enthusiast of Britten's operas when I showed him the earliest publicity designs for Christopher Alden's production, you could set them all in a school, even Gloriana - what about headmistress Bess and head prefect Essex? But could you squidge everything into the one shape, I wondered? At ENO, it makes instant sense in the composer's near-perfect musical translation of Shakespearean wood magic that Oberon is the schoolmaster who prefers changeling pre-pubescents to now-adolescent, discarded Pucks. That's the strongest of starting points.

With regional youth orchestras dropping from a thousand short-sighted, wholesale cuts - flagship Leicestershire the latest under threat - it should be enough just to celebrate 60 seasons of the LSSO, safe for now under the City of London's munificent wing. But last night was more than just another fun concert. No one ought to miss any appearance of the, ahem, enormously charismatic Leif Segerstam, composer of 244 symphonies to date and master orchestral trainer, who always goes for depth of sound rather than surface glitter.

Despite footsteps in the snow, as creepily characterised by Debussy's prelude of the same name, and sleighbells to launch a childlike symphonic journey, interior illumination should have been at the core of this concert. Sadly, given Colin Matthews's refined but fussy designer lighting in his Debussy orchestrations, a low-wattage Rimbaud/Britten zoo from one-tone soprano Christine Schäfer and hard sunbeams failing to probe the inner mysteries of the tomb-effigies Mahler envisaged in his Fourth Symphony's slow movement, it wasn't. Fortunately Vladimir Jurowski found novelty enough elsewhere to keep us from slumping in the semi-dark.

If you were one of the world's top soloists but with a limited concerto stock - as woodwind players' tend to be - wouldn't you find it more rewarding to work as a principal in the orchestral ranks? That's the ideal, surely, but few carry it out in practice. Nicholas Daniel, the beefiest-sounding oboist to appear on the scene since the great Maurice Bourgue, is one who does. Last night he not only shone in the bright ensemble of Beethoven's Second Symphony; he also scored a triumph with a tough new gift to him and the Britten Sinfonia, James MacMillan's latest teeming-with-life concerto.

To paraphrase a cliché, it’s rare to leave a theatre humming the lighting. But here, Matthew Haskins’ lighting designs help make this production so powerful and evocative, whether projecting grotesque, distorted shadows on the back wall of Madeleine Boyd’s claustrophobic set, or illuminating characters’ subtle facial expressions. Dawn and dusk are both beautifully realised, and when we’re finally shown a brightly lit stage at the opera’s shocking close, you almost have to shield your eyes.