Bernadette Peters is part of the starry cast in Stephen Sondheim’s ‘Old Friends’ at the Gielgud [Danny Kaan]

WHEN Stephen Sondheim died two years ago the world of lyric theatre lost its modern master. His achievement rose above divisions between Broadway musical and opera. And for proof, go see the tribute show Old Friends that’s opened at the Gielgud Theatre, Shaftesbury Avenue. A cabaret-review of Sondheim numbers, it plays on a more epic scale than those of the past – with an electrifying energy and touching power as a memorial to his greatness.

One after another come the classic songs, on a conveyor-belt of genius. They’re delivered by a starry cast. And at its centre is the legendary Bernadette Peters whose career has been so closely connected with Sondheim over the decades she’s like his surviving soul.

At 75 the voice is fragile now (the “old” in Old Friends no exaggeration), and the show makes sparing use of it. But she remains extraordinary: the auditorium erupts when she’s onstage. And she’s the only septuagenarian imaginable who could get away with playing Little Red Riding Hood – as she does here in scenes from Into the Woods.

With Lea Salonga as a no less sensational co-lead, Old Friends is a reminder that although the Sondheim repertoire is done these days by opera singers and in opera houses, it belongs to Broadway where an open-hearted lack of inhibition gives it something else. Closer to dynamite. This show is an explosive joy: I haven’t had a better theatre evening since I don’t know when. Five stars are not enough, it’s worth at least ten. Runs to January. gielgudtheatre.co.uk

• Bringing a different sort of American dazzle to London, the magnificently-named choral group Roomful of Teeth is over from New York with a programme of the sometimes off-the-wall but always virtuosic vocal works in which they specialise. And they don’t win Grammys for nothing. Hear them Oct 7 at the Guildhall School’s Milton Court. barbican.org.uk

• At the Barbican this week, Antonio Pappano is asserting his presence as the LSO’s chief conductor designate now that Rattle has gone. On Oct 8 he introduces a new Violin Concerto by Fazil Say. And Oct 12 he conducts the suddenly ubiquitous Kirill Gerstein in Thomas Ades’ Piano Concerto – which Gerstein performed only a few weeks ago at the Proms. Worth seeing again, though, for the fireworks of it. barbican.org.uk

• Joseph Phibbs is, for my money, one of the truly commanding talents in contemporary British music; and Wigmore Hall must think so too because it has an entire day of his work on Oct 7 with concerts morning, afternoon and evening. A perfect introduction for newcomers, with a premiere thrown in.

Also at the Wigmore, Oct 8, is one of the finest young string quartets around, the German-based Leonkoro (whose name means Lionheart in Esperanto apparently). I saw them recently in the Cheltenham Festival and was awestruck by their energy, intelligence and brilliance. They’re the real thing. wigmore-hall.org.uk

• Meanwhile, English Touring Opera bring their new production of Rossini’s Cenerentola to Hackney Empire for one night, Oct 7 (hackneyempire.co.uk). And the Royal Opera revives its competent if stiff Oliver Mears staging of Rigoletto, with Pretty Yende as Gilda, Oct 12-Nov 28 (roh.org.uk).