Announcing plans for his first season as chief conductor of the London Symphony Orchestra, beginning in September, Simon Rattle reminded us that British composers now lead the world in variety and talent. In the current national mood, this simple statement gave cheer. News of a golden age may not surprise those of us whose job, and mostly delight, is to report the evidence on a weekly basis. Yet sometimes a figurehead such as Rattle has to add his voice for the point to register. Not that it’s a sudden discovery to him either. As a 23-year-old in 1978, one of his first career breaks was to conduct the premiere of Peter Maxwell Davies’s Symphony No 1.

That commitment to colleagues older and younger, of all nationalities, has never faltered. This is about music, not jingoism. It just happens that several – Thomas Adès, Julian Anderson, Harrison Birtwistle, Oliver Knussen – are from the UK. Mark-Anthony Turnage (b1960) is another. He was the first composer in association with the City of Birmingham Symphony Orchestra in Rattle’s era there, long before anyone knew what such a creature might be or do. That early kinship, dating back to the 1980s, has lasted. On Thursday Rattle and the orchestra gave the world premiere of a substantial new work by Turnage, Remembering, a co-commission between the LSO, Berlin Philharmonic and Boston Symphony.

Players and conductor had already filled the Barbican twice over for semi-stagings, by Peter Sellars, of Ligeti’s Le grand macabre, a late 20th-century anarchic landmark that still bares its teeth. Sellars came up with an almost reasonable combination of video, hospital bed frippery and post-nuclear horror, with acres of vacuum-pack plastic. Never mind whether it’s what Ligeti intended. The music, rampantly and gleefully played, offered all the necessary wit and subversion. Much has been written about it already. In a full week, this space should go to Turnage.

His new four-movement work, lasting half an hour, is subtitled “In memoriam Evan Scofield”. It was written for the son of Turnage’s jazz colleague, guitarist John Scofield. Evan died of cancer, aged 26, in 2013. Knowing this inevitably gave a heightened intensity to the performance, yet Remembering was about life as well as death. An energetic, pulsating figure, seesawing from double basses to high brass, ignites the piece. Taut rhythmic patterns and swift melodic motifs in each section suddenly break off and shift to fateful, drum-heavy, climactic sounds. The writing is tonal, buoyant, impassioned. A variety of bells, plus piano, celesta and saxophone, shape the orchestration, and offset the dark string colours.

At Rattle’s own insistence, there are no violins. Violas have prominence, especially in the quietly rhapsodic, melancholy last movement, written first, and originally a piano work. These are first impressions. We can listen again. The concert was broadcast live – together with a furious, exhilarating, if at times skin-of-the-teeth performance of Mahler’s Sixth Symphony. Part of the excitement was in realising the degree to which Rattle, exacting to the last, will challenge every member of this fine orchestra: no room for complacency or sticking to the old, safe ways. Each is playing for his or her life. This is the start. There will be plenty more to say.

Harrison Birtwistle’s The Last Supper (2000), mythic rather than personal, explores that moment when human experience turns to ritual. A dinner between men starts with disputatious questioning – why are we here, will Jesus come, where is Judas? – and ends as symbolic atonement for 2,000 years of history. Robin Blaser’s libretto, in which God makes scant appearance, deals in loyalty and betrayal. This remains an ever fertile subject: the Israeli writer Amos Oz considers similar issues in his novel Judas (2016).

Birtwistle’s two-hour opera, given a rare and excellent performance by the BBC Scottish Symphony Orchestra, BBC Singers and soloists conducted by Martyn Brabbins (broadcast on Radio 3 next Saturday), is a series of dramatic tableaux. As with Turnage’s new work, there are no violins. A strange, smoky accordion and much growling low woodwind and brass dominate. The unseen Chorus Mysticus and the electronic Chorus Resonus arrest and interrupt the action. In Victoria Newlyn’s effective semi-staging this was achieved by the disciples freezing into the physical gestures of Leonardo da Vinci’s definitive painting.

One female soloist – the imaginary Ghost, fearlessly sung by the wonderful Susan Bickley – unites past and present. Each of the 12 disciples – two countertenors, five tenors, two baritones and three bass – has his own vocal character. Surtitles would have helped, though by the time Christ entered and the ritual washing of feet began, all became distinguishable. With a top-notch cast led by baritone Roderick Williams as Christ, Benedict Nelson, Daniel Norman and more, an aural icon was created. When The Last Supper was new, in a pre-9/11 world, some of its concerns felt outmoded. How wrong we were. Now it has proved its enduring pertinence.

At the Royal Opera House, two revivals demand pithy attention. George Benjamin’s Written on Skin (2012) is back for a first revival, with many of the same star singers, Barbara Hannigan, Christopher Purves, Iestyn Davies among them. The composer, another of Rattle’s British throng, also conducted, the score sounding more sensuous than ever, with its sultry textures and bright, squally flares. On the second night, Georgia Jarman, who shares the female lead with Hannigan, sang Agnès. Jarman is equally deft in the dizzying coloratura, her voice a little richer, but her stage style is strikingly reserved, casting the action in a new light. James Cleverton, singing the role of the Protector from the side while a vocally indisposed Purves acted, brought equal freshness, compensating for the awkwardness this emergency solution causes.

In contrast, Verdi’s La traviata, in Richard Eyre’s feast of a staging, new in 1994, returned for its 14th revival, one of the best yet. Orchestra and chorus were on tip-top form, cast impressive. Conductor Daniele Rustioni kept the place alive and pliant but never too urgent. The two ROH debutant principals, the Lebanese-Canadian soprano Joyce El-Khoury as Violetta and Russian tenor Sergey Romanovsky as Alfredo, deserved the excited applause. El-Khoury’s voice, a mix of fragility, brilliance and some indefinable, almost abrasive texture, is an ideal match for Violetta’s raw and tragic spirit. And who wouldn’t fall for this pure-voiced Alfredo, austere yet ardent. For spectacle and immediacy, this opera, in this staging, is hard to beat. Find an opera novice and go. I did. Her pleasure doubled my own.

• Written on Skin is in rep at the Royal Opera House, London, until 30 January. La traviata is in rep until 4 July

• The LSO/Rattle Turnage and Mahler concert is available to watch on Medici TV
  
  
• This article was amended on 22 January to correct the name of the BBC Scottish Symphony Orchestra