In 1966, Clarke, along with several Hollies bandmates, assisted in The Everly Brothers recording of their album, "Two Yanks in England", which featured Everly cover versions of mostly Hollies songs co-written by Clarke. Clarke-Nash-Hicks composed The Hollies' albums: "For Certain Because" (1966), "Evolution", and "Butterfly" (both 1967). Their UK hit singles compilation "The Hollies' Greatest Hits" topped the UK Albums Chart in August 1968. After 1967, Clarke began writing solo songs under the team banner, notably: "Lullaby To Tim" (dedicated to his son, though sung by Nash), "Heading for a Fall", "Water on the Brain", and "Would You Believe?". Besides the full composing team, Clarke also wrote songs with Nash such as "Try It", "Wishyouawish" (1967), "Tomorrow When it Comes", "Jennifer Eccles" and "Wings" (1968). Clarke assumed more of a figurehead profile as front man of the Hollies following Graham Nash's departure from the group in December 1968. Clarke was the sole lead singer on "Hollies Sing Dylan" (a UK No. 3 album in early 1969). Clarke has sole credit for songs such as "My Life Is Over With You", "Goodbye Tomorrow", "Not That Way at All", "Marigold" (1969), "Mad Professor Blyth", "Separated" (1970), "Row the Boat Together" and "Hold On" (1971). Also, Clarke helped Nash's replacement, Terry Sylvester, develop as a songwriter, teaming with him to write a number of songs including "Gloria Swansong", "Look at Life" (1969) "I Wanna Shout", "Man Without a Heart" and "Perfect Lady Housewife" (1970). Keen to launch a solo career due to Nash's success in Crosby, Stills & Nash, Clarke left the group in 1971. He was replaced by the Swedish singer Mikael Rickfors, who was formerly with Bamboo. Clarke went on to release two solo albums – "My Real Name Is " (Epic, 1972) and "Headroom" (EMI, 1973). After Clarke left The Hollies, "Long Cool Woman in a Black Dress", a song from their 1971 album "Distant Light," which he had co-written with songwriters Roger Cook and Roger Greenaway, and on which Clarke sang lead and played lead guitar, became an international hit single, reaching No. 2 in the US (their most successful single ever there) and No. 32 in the UK Singles Chart.