'Core Seven' period
Pinder was partly responsible for the choice of young Swindon guitarist, vocalist and songwriter Justin Hayward to replace Laine. It was Pinder who phoned Hayward and collected him from the railway station. Rod Clarke briefly replaced Warwick as bassist until John Lodge was recruited as bassist/vocalist, completing the 'classic' Moodies line-up.
After trying to continue with R&B material, the band decided to drop covers and record only original songs after an audience member told them their R&B material was rubbish. Hayward's "Fly Me High" was the first single from the revised line-up, released on Decca in early 1967, with Pinder's old-style rocker "Really Haven't Got the Time" as the B-side. A recorded but unreleased Pinder song from this time (1967) was the jazz/blues ballad "Please Think About It". It was included on the Caught Live + 5 double album issued by Decca in 1977.
Pinder acquired a second-hand Mellotron from Streetly Electronics, and after removing all the special effects tapes (train whistles, cock crows, etc.) and doubling the string section tapes, used it on numerous Moody Blues recordings, beginning with their single "Love and Beauty", a flower power song written and sung by Pinder, which was his only A-side after 1966. He introduced the Mellotron to his friend John Lennon, and the Beatles subsequently used one on "Strawberry Fields Forever".
His "Dawn (Is A Feeling)", with lead vocals by Hayward and Pinder singing the bridge section, opened the Days of Future Passed album. Pinder also contributed "The Sunset" and narrated drummer Graeme Edge's opening and closing poems, "Morning Glory" and "Late Lament". Days of Future Passed had been planned as a stereo demonstration album for the Decca Deram label, combining rock and orchestral music. It sold more than a million copies in the US.
Pinder, Moody Blues recording engineer Derek Varnals and long-time producer Tony Clarke (a Decca staff producer assigned to them from "Fly Me High" onwards), devised an innovative way of playing and recording the unwieldy Mellotron to make its sound flow in symphonic waves, rather than with the instrument's usual sharp cutoff. This symphonic sound provided the basis of the musical style of the band's seven major albums between 1967 and 1972.
Pinder was one of the first musicians to use the Mellotron in live performance, and he had to rely on the mechanical skills he had gained from his time as an engineer with Streetly Electronics to keep the instrument functioning. In the band's first US concert, the back of the Mellotron fell open and all of the tape strips fell out. Pinder got the instrument back into working order in 20 minutes while the lighting crew entertained the audience by projecting cartoons.
On Moody Blues recordings from 1967 onwards, in addition to the mellotron, organ and piano, Pinder played harpsichord, Moog synthesizer, various other keyboards, as well as autoharp, tanpura (tambura), cello, bass, acoustic and electric guitars, and percussion including tabla and tambourine. (Hayward often boasted that his bandmate was the best tambourine player in the world.) He also sang vocal harmonies and lead vocals from 1964 to 1978 and was the group's main musical arranger up to 1978. The 1969 concert on the Caught Live + 5 album and the Live at the Isle of Wight Festival 1970 DVD show Pinder and Thomas acting as the group's onstage spokesmen.
Pinder wrote and sang several of the band's more progressive, even mystic, numbers, including "The Best Way to Travel" and "Om" (both from 1968's album In Search of the Lost Chord on Deram Records), plus the innovative symphonic rock piece "Have You Heard/The Voyage/Have You Heard (part two)" which concluded their 1969 album On the Threshold of a Dream. Parts of this track later featured on the Loving Awareness jingles on Radio Caroline during the 1970s. Pinder also continued to the narrating of Edge's poems, notably "The Word" (1968); "In The Beginning" (with Edge and Hayward) and "The Dream" (both 1969); and "The Balance" (1970).
On Edge's song "Higher And Higher" (1969), Pinder's Mellotron simulated the sound of a rocket blasting off to open the To Our Children's Children's Children album, for which he wrote and sang "Sun is Still Shining". He also sang lead vocals on a rare co-written song with John Lodge, "Out and In". Pinder's Mellotron was prominent on tracks such as Edge's instrumental "Beyond" and the Hayward–Thomas closing track "Watching And Waiting".
Pinder's earlier non-album song "A Simple Game" (1968), for which he won an Ivor Novello Award, was used as the B-side of the group's UK hit single "Ride My See-Saw" from In Search of the Lost Chord. This song and Pinder's "So Deep Within You" from On The Threshold of A Dream (1969) were covered by The Four Tops in the early seventies.
On 12 October 1968, the Moody Blues cut a version of "A Simple Game" featuring Hayward on lead vocal, considering the song as a potential UK single, but this recording was not issued and the version sung by Pinder was used instead. The rare 'Hayward' version appeared as a bonus track on the remastered CD version of In Search of the Lost Chord in 2006. In 1969 the Moody Blues established their own record company, Threshold Records, and in 1974 included the song on a compilation double album, This is the Moody Blues, with the title "Simple Game".
Pinder's 1970 album track "Melancholy Man" from A Question of Balance became a No. 1 hit in France. His "How is it (We Are Here)" from the album sessions, with the working title "Mike's Number One", surfaced later as a CD release. On all three songs Pinder sang lead vocals. His composition and lead vocal, "My Song", a deep, reflective, and atmospheric piece, concluded the Moody Blues' 1971 album Every Good Boy Deserves Favour. He took co-credit with the entire band for the album's unusual opening track, "Procession", which was an attempt to illustrate the evolution of vocal and musical harmony, and he sang a featured co-lead vocal and solo with Hayward, Lodge and Thomas on Edge's song "After You Came".
In 1971, Pinder guested on John Lennon's Imagine album on "I Don't Wanna Be A Soldier (I Don't Wanna Die)" and "Jealous Guy". He played tambourine rather than the mellotron he had intended to use because, he said, the tapes in Lennon's mellotron looked like "a bowl of spaghetti".
In 1972 the Moody Blues, then at the height of their popularity, recorded the Seventh Sojourn album, which included two songs written and sung by Pinder: "Lost in a Lost World" and "When You're A Free Man", dedicated to Timothy Leary. For this album he played the similar-sounding but less troublesome tape-based Chamberlin keyboard.