★★★★☆

And there shall come to pass at the end of days when every recording that was ever made is gathered together and ascended to heaven for all to hear. And even as the chariot rises so a voice will cry, “I’ve just found some more in a radio archive.”

The latest box is packed with 20 CDs of breath-catching astonishments

The ICA Classics label, founded by the artists agent Stephen Wright, has been scouring the BBC for concerts of the 1960s to 1980s that were taped but never released. The latest box is packed with 20 CDs of breath-catching astonishments, and I do not use the term lightly.

If you have no interest in hearing Sviatoslav Richter play Schubert sonatas at a Royal Festival Hall so full that it sounds warmer than I have ever known, if this snippet of information does not cause palpitations and make you want to be young again, then you have probably strayed into the wrong part of the metaverse and need to retap your search term. Richter, unique as he was, never sounded quite like this.

There’s more. Carlo Maria Giulini conducts the Britten War Requiem at the Royal Albert Hall, with the composer conducting the secondary chamber orchestra and a Polish soprano called Stefania Woytowicz chilling the blood more than any high-hooter on record. You might want to skip Arturo Benedetti Michaelangeli in the Grieg concerto — a mismatch made in a BBC canteen — but Pierre Boulez conducting Clifford Curzon in Beethoven’s Emperor Concerto? Now that’s a collector’s item if ever there was.

I’m not going to recite a catalogue aria of contents. This box is a giant dipper of delights that lacks the distraction of explanatory notes or cover art. It delivers the music in surprisingly lucid pre-digital sound. Opening it is like falling through a hole in the floor into a lost world where the great French cellist Paul Tortelier plays Elgar, the revered Rudolf Kempe conducts Tippett, and Berg and the massive John Ogdon reduce the two Liszt concertos to matchsticks. Did I mention Serkin and Szell in Beethoven? Klaus Tennstedt’s 1980 Mahler 7th from the Edinburgh Festival? Unmissable hours of an unearthly past. Do not walk on by.