Deep Purple are an English hard rock band from Hertford, Hertfordshire. Originally known as Roundabout, the group formed in March 1968 featuring vocalist Rod Evans, guitarist Ritchie Blackmore, bassist Nick Simper, drummer Ian Paice and keyboardist Jon Lord. This first lineup of the band, known as Mark I, released three albums within the space of a year – Shades of Deep Purple, The Book of Taliesyn and Deep Purple – before Evans and Simper were fired from the band at the request of Blackmore and Lord. Mark II of Deep Purple saw Ian Gillan and Roger Glover replace Evans and Simper, respectively, in the summer of 1969. This lineup of the band has since been identified as their most successful, with their next four albums reaching the top four of the UK Albums Chart, including number-one albums Fireball and Machine Head.