Next Saturday evening, Janet Jackson will take to the Pyramid Stage. It’s too soon to say whether the 200,000 festivalgoers will be sunburnt or mud-caked — probably both — but she and her dance troupe will be resplendent in boas, sequins, catsuits and leather couture. “I’ve never been to Glastonbury,” she says. “Is it really always muddy? I’m excited. Hopefully they’ll like us.”

It’s certainly an imaginative booking. Janet Jackson wasn’t just big in the 1980s and 1990s. She was huge. A global icon. When Rhythm Nation was released 30 years ago, it broke all sorts of records and won all sorts of awards. Her 100m-plus album sales and counting make her one of the most successful recording artists of all time. In 1996, she