The devil wore all manner of outlandish attire in last night's chameleonic programme devised by Peter Ash, the London Schools Symphony Orchestra's challenging artistic director.

In youth we trust. That can be the only motto worth anything for 2020, as the world goes into further meltdown.

So it was startling, stunning and cathartic, two days after the big downer of 3 January – the American horror clown seemingly in competition with the Australian apocalypse – to witness 164 teenagers under a conductor they clearly adore, Jaime Martín, making their voices heard, sometimes literally, in 20th century music of fear, anxiety, protest, violence and just a smidgen of hope.

Notable anniversaries provided the ballast for this year’s raft of exhibitions; none was dead weight, though, with shows dedicated to Rembrandt, Leonardo and

The Barbican, a week before Christmas, and it’s British folk-rock legends Steeleye Span’s last gig of the year, a year in which its vigorous seven-strong line-up – featuring a new recruit in the shape of former Bellowheader Benji Kirkpatrick – celebrated a half century of Span by releasing a strong new album in Est’d 69.

What a jolting coincidence that one of the 20th century's angriest symphonic beasts should have a rare unleashing on a night of high national anxiety. Whether Vaughan Williams spewed forth his Fourth Symphony in response to darkening European clouds in 1934 or as a sublimation of sexual frustration, given his unhappy domestic life at the time, it hit us all hard last night.

“How many times have you heard the conductor sing?” asked William Christie after the final number, but before the two encores, of Sunday night’s 40th birthday celebration for his ensemble Les Arts Florissants. Well, lovers of old recordings know that you sometimes get plenty of impromptu vocalisation from the likes of Bernstein and Barbirolli.

There are encores and encores – most a friendly, minimal farewell gesture from the soloist; some a jolly, festive unwind after a particularly taxing piece. And then there’s the luxury free gift that Sir András Schiff bestowed on us during the second of two Barbican concerts with Iván Fischer and his Budapest Festival Orchestra.

This family concert – “Total Immersion: Lift Off!” – was basically a small-scale rerun of this year’s CBeebies Prom, that one entitled “Off to the Moon”. The Prom had a space theme, to mark the 50th anniversary of the Apollo 11 moon landing, and this Barbican concert just came in under the wire, still in the anniversary year, even if the commemorative events from the date itself, back in July, now seem distant.

A few years ago it would have been hard to envisage proto-punk maniac Iggy Pop being a star feature of the EFG London Jazz Festival. His last few albums, though, have been heavily flecked with jazz, and let’s not forget that as far back as The Stooges’ 1970 album Funhouse, free jazz sax squalling was part of the mayhem.

The megastars are here at the Barbican, for an intensive three days in the case of the LA Phil and Gustavo Dudamel, throughout the season as the hall shines an "Artist Spotlight" on pianist Yuja Wang. Despite a shallow opener showcasing the individual talents of the Los Angeles principals and daft, rollicking Sousa at the end, there was a seriousness of intent and depth of focus that belied the touring glitz.