By Tobias Carroll Earlier this month, a host of musicians took part in celebrating Queen Elizabeth II’s Platinum Jubilee. Among them was Rod Stewart, who performed “Baby Jane” and then covered “Sweet Caroline,” the latter of which he described as “nerve-wracking” in an interview with the BBC. But while the bulk of the royal family seemed pleased by Stewart’s performance, another beloved musician was far less taken with it. That would be Elvis Costello, who expressed his bewilderment over the BBC asking Stewart to perform a certain Neil Diamond song as opposed to one of his own hits. As Ultimat…