After a spell in the US Army during the Vietnam War, he moved to Los Angeles in 1968, and the following year, forged a successful 11-year working collaboration with young British songwriter-musician Brian Potter after the two met while Lambert was in London in 1969.

Lambert and Potter joined a new record label in Los Angeles, Talent Associates, founded by producer-director Steve Binder, where they worked as producers and songwriters.

They signed the Original Caste (One Tin Soldier) and worked on developing the artist roster, which included Seals and Crofts.

They wrote and produced for the Grass Roots, Hamilton, Joe Frank & Reynolds,[4] Gayle McCormick, the Four Tops, Original Caste, Coven,[5] Dusty Springfield and Richard Harris, often working with A&R chief/producer Steve Barri.

They produced the Righteous Brothers' major hit "Rock and Roll Heaven" which revived the duo's recording career in 1974.