How do you improve on a masterpiece? Giles Martin knows better than most, after accepting the potentially double-edged task of overseeing the 50th anniversary reissue of Sgt Pepper’s Lonely Hearts Club Band.

The Grammy-winning producer, whose previous credits include The Beatles’ Love album and 2016’s Live At The Hollywood Bowl, worked with mix engineer Sam Okell and an expert team of audio restoration specialists on the project at Abbey Road Studios in London.

“I’m always nervous about these things, but ...