Eric Lambert was born in Stamford, England, but left the place of his birth when one year old. The family moved to Sydney where Lambert was educated at Sydney Boys' High School and Manly High School. He joined the AIF in 1940, serving in the Middle East, New Guinea and Singapore. When the war ended, he was a member of the Australian Army Education Service, assisting with the recovery of Australian prisoners of war from Changi. References to Lambert as 'an Australian Hemingway' are derived from the two men both serving as soldiers and writing about war.
A compulsive writer, he regularly engaged in polemic in the correspondence columns of The Age. He wrote biography and novelised versions of film scripts under the names of Frank Brennand and George Kay. Work under the other assumed name of D. Brennan has not been identified yet. He used autobiographical material frequently; for example, the protagonist of The Drip Dry Man is a journalist and script writer. He also wrote some verse and short stories. He received a Commonwealth Literary Grant in 1950, which enabled him to finish writing The Twenty Thousand Thieves.
Soon after his return to Australia, when he lived in Melbourne, Lambert formed a significant friendship with Frank Hardy: '[they] talked of writing incessantly; they were utterly possessed by it...the two men were inseparable' (O'Leary The Desolate Market: A Biography of Eric Lambert, 1974, 37). The friendship came to an acrimonious end by the mid-1950s but before then, Lambert joined the Communist Party at Hardy's instigation. He was active in left-wing literary circles for almost a decade after the war; he joined the Realist Writers' Group, the literary organisation of the Labor Movement, and became a member of the first editorial board of Overland. In 1955, he went to live in England, where he divorced his first wife, Joyce Margaret Boyd Lambert, and remarried.
His most successful work was The Twenty Thousand Thieves, which he self-published by registering the Newmont publishing house (subsequently taken over by Frederick Muller, England). The Twenty Thousand Thieves has had numerous editions and reprintings and has become a classic of war literature. Literary friends included Brian Fitzpatrick, Dymphna Cusack, and Dame Mary Gilmore.