Siouxsie has always been open about her love of the likes of Roxy and Bolan. Indeed, the Banshees were playing 20th Century Boy live in 1977.
She discusses what she liked (Johnny RememBer Me, Leader of the Pack) pre that period in the rather good The Auth Biog by Mark Paytress. Well worth a read even if she does come across as a bit of a prat at times!