Frederick J. Mills began his career with the postal department, training as a telegraphist and working at Eucla, Western Australia, before moving to the Greneral Post Office, Adelaide. He became involved with the South Australian Literary Societies' Union., and edited 'Sundry Scintillations' for the Saturday Evening's Journal under the pen-name of 'Twinkler'.
In 1923 he resigned from the Post Office and became State General Secretary of the Boy Scouts' Association. In 1927 he established the 'Twinkler' Boys' Club on Radio 5CL as an auxiliary to the Scout movement, and ran it until 1945. With 7000 members, the club raised large sums of money for the Adelaide Children's Hospital. A frequent visitor to the hospital, he also established the 'Twinkler' Invalid Club. He ran a magazine for children, The Twinklerite, 'to cheer up and help blind, deaf and dumb, crippled and invalid children'.
Mills was also a strong supporter and Vice-President of the 'Cheer-Up Society' for the support of military forces, and in 1920 wrote the story of the movement, Cheer Up: A Story of War Work. An enthusiastic proponent of humour and a positive outlook, he published several books of Australian stories, donating the proceeds to the Returned Soldiers' League. Several of these ran to a number of reprints. He helped establish the Violet Day of remembrance for fallen soldiers (1915), and became executive officer of the Wattle Day League. He founded and edited a magazine for the R.S.L. When he retired from the Boy Scouts' Association in 1927 due to poor health, a public testamonial raised £600.
Mills was made an MBE in 1928.