In 1960 Souter was awarded the W.G. Walkley National Award for Australian Journalism.
His books have included New Guinea: The Last Unknown (1963); A Peculiar People (1968), an account of the New Australia settlement in Paraguay; The Idle Hill of Summer: an Australian Childhood (1972); Lion & Kangaroo: The Initiation of Australia 1901-1919 (1976).
In 1983 he was commissioned to write a narrative history of the Parliament of Australia to commemorate the Bicentenary of European occupation of Australia in 1988. This was entitled Acts of Parliament.
Members of Aboriginal, Torres Strait Islander and Maori communities are advised that this catalogue contains names and images of deceased people. All users of the catalogue should also be aware that certain words, terms or descriptions may be culturally sensitive and may be considered inappropriate today, but may have reflected the author's/creator's attitude or that of the period in which they were written.