Seymour was born in
Fremantle,
Western Australia. After that he was brought up by his sister May and her husband, Alfred Chester Cruthers. He was educated at
Perth Modern School, leaving at 15 after failing to complete the Junior Certificate. He found work as a radio announcer in a commercial radio station 6PM. During his two years there he wrote a number of short radio plays that were broadcast live. In 1945 he moved to
Sydney,
New South Wales, where he worked as an advertising copy-writer with 2UE. He returned to Perth after the war where he worked as a free-lance writer for
ABC Radio. Seymour became ABC Radio's film critic. He joined a commercial radio station 6KY as an announcer and copy-writer and after six months was offered an announcing post at the ABC. In 1949, he met Ron Baddeley, an
RAAF veteran, and the two would become life partners. Seymour left Australia in 1961 and worked in London as a television writer, producer and commissioning editor with the
BBC, and as a theatre critic for
The London Magazine. From 1966 to 1971 he lived in
İzmir,
Turkey, where Ron Baddeley had gained employment as an English teacher. There Seymour wrote a novelisation of
The One Day of the Year, and another novel
The Coming Self-Destruction of the United States of America, as well as stage plays and magazine articles. From 1974 to 1981, he was a script editor and occasional producer with
BBC Television, after which he returned to freelance writing. In 2003, after a partnership of almost 55 years, Ron Baddeley died at age 80. and died in an aged care facility in
Elizabeth Bay in 2015, aged 87. ==
The One Day of the Year==