John Ryan reports that Sky Demons #1 was a comic that 24-year-old Norman Clifford offered to Southdown (Panel by Panel, p. 203) in the early 1950s. He went on to also write and draw Dare Devil Comics, Billy Battle Sky-Fighter, Sky Demons, Christmas Comic and Thrilling Space Adventures He also drew several covers for the publisher's long-running Buck Rogersreprints.

in 1956 and 1957, Clifford also did somic strips 'Olympixies' and 'Adventures in Tiny Land' for the children's pages of New Idea magazine (Southdown).

The lettering for his comics were usually done by his mother.

From the 1980s, Clifford extensively painted Australian historical aviation themes. He illustrated the 1981 edition of world war II flying ace Arthur Henry Cobby's autobiography, High Adventure (Melbourne: Kookaburra Technical Publications).

He was commissioned by Hawker de Havilland Australia to do a collection in tribute to the Australian aviator and Hawker founder, Harry Hawker. A calendar of 12 paintings was published for 1998. He also compiled a history Australian Flying Corps (AFC), published May 2018. A series of Australia Post pre-paid envelopes including his artwork was released in 2016.

For the Sport Aircraft Association of Australia, he painted a poster to commemorate the last Mangalore Air Show in 1989, an event that had been held at the Mangalore Airfield in Victoria since the end of WWII.

Clifford painted covers for two of Macarthur Job's books on aviation safety, Disaster in the Dandenongs (2008) and Into Oblivion (2010).