Back in England in early June, the decision taken had to be kept secret until the promotional tour for the British release of "The Book of Taliesyn" was completed. Meanwhile, the search for a new singer to replace Evans began and Blackmore asked for help in this task from his old acquaintance Mick Underwood, at the time drummer of the British rock band Episode Six. Underwood recommended Episode Six singer Ian Gillan, whom Blackmore and Lord contacted at a London gig. Gillan, who did not see a future in his then current band, was enthusiastic about joining Deep Purple and involved bassist Roger Glover, with whom he formed a songwriting duo. According to Simper, his replacement with Glover was initially not planned and was due to the creative togetherness of the two Episode Six members. Gillan convinced the reluctant Glover to audition for Deep Purple and the two soon found themselves torn between the new band, which gladly welcomed both of them, and obligations with Episode Six for the completion of a UK tour. Evans, Simper and Episode Six's management were kept unaware of these events and of the fact that the new line-up was already active in writing and rehearsing new songs. In between gigs all over the country, Deep Purple had rehearsed the song "Hallelujah" with Evans and Simper to be released as a new single, but it was recorded in secret on 7 June by the fresh Mark II line-up at De Lane Studios instead, with Glover still acting as a session musician. The final show of the Mark I lineup was in Cardiff on 4 July 1969, and the Mark II lineup debuted live at The Speakeasy Club in London on 10 July. The final show played by Gillan and Glover with Episode Six was in Little Bardfield on 26 July 1969. The single "Hallelujah" was released in late July in the US and the UK and featured an edited version of "April" as B-side, the final original appearance on vinyl of the Mark I formation.