As a songwriter first and foremost, Mick Jagger has always found it hard to silence that little jealous voice when he hears a song he wishes he’d written himself. It’s a sucker punch to spend so much time labouring over your own music, only to switch on the radio and hear a song that suddenly makes everything you’ve been doing feel lightyears behind. In an instant, the landscape has shifted, your own work feels dated, and it’s time to get back i…