He was educated at
Sydney Grammar School and joined 2GB as an office boy in 1941. He took on occasional writing and announcing roles and was involved in production of
John Dease's
Quiz Kids. He next worked in
Britain with
Peter Sellers and Michael Bentine in the 1957 television comedy skit show ''Yes, It's the Cathode-Ray Tube Show
. The following year he moved to Britain, and for 20 years he was seldom out of work but maintained ties with Australia in regular hookups with John West for his radio programme The Showman
. In 1971 he appeared in the acclaimed BBC drama Elizabeth R'' as forger
Thomas Phelippes. In 1977 he settled in the Sydney suburb of
Glebe. He appeared in stage and television productions, and took on the positions of federal treasurer for
Actors Equity. He was involved in the doomed campaign to save the
Regent Theatre in Sydney from demolition and helped manage the Actors' Benevolent Fund. Throughout the 1980s and 1990s Nettheim appeared in guest roles in numerous Australian TV mini series and serials, including
Prisoner,
Sons and Daughters, and
A Country Practice. ==Death==