Walker was born in Hay, New South Wales, the son of Frank and Ethel Walker. Walker attended Newington College (1934-1936) before entering the University of Sydney to study arts whilst a resident of Wesley College. He joined the Sydney Morning Herald as a journalist in 1938.
Following World War II, Walker returned to the Herald and was posted to the United States of America where he worked with Reuters-Australian Associated Press. His reporting of McCarthyism brought him into conflict with Joe McCarthy and his wife's visa was cancelled. He then worked for Reuters in London before joining The Herald .
In 1956 he joined the Australian Government Information Service and worked from London on immigration publicity. He revolutionised Australian immigration advertisements in Europe by showing something symbolic of Australia without spruiking immigration as such ads were banned in Scandinavia. He became Australian press attache in Germany in 1960.
Walker retired to Budgewoi, New South Wales in 1980 and wrote a number of military histories. In 1999 his wife died and he died in 2008 survived by his second wife, Erika, and two sons, Peter and Frank.