Earlier this summer, guitarist Tony Iommi and bassist and lyricist Geezer Butler returned to Birmingham for the opening of an exhaustive exhibition about Black Sabbath, the band they formed in the city 50 years ago. Birmingham Museum & Art Gallery is currently home to a vast collection of both the band’s own memorabilia and a staggering array of fan tributes. Asked if there was anything not present in the collection that they expected to see, Butler couldn’t resist a quip: “Ozzy?”