Mallaby was born in Hartlepool, United Kingdom, and moved to Australia with his parents when he was 16. His father was a policeman. Mallaby's first jobs were signwriting and crayfishing. He was married twice, the first time in 1968. He suffered a stroke in 1994, and subsequently used a wheelchair. He died of congestive heart failure in 2004. He was survived by his widow Lenice, sons Guy and Luke, and daughter Kirsti from his first marriage.
Career
Mallaby made his acting debut at the Adelaide Festival of Arts, but soon obtained TV roles in Melbourne. He played Detective Peter Barnes in the crime series Homicide in episodes 131 to 395 from 1967 to 1973, representing more than half the series run. Along with Alwyn Kurts, Leonard Teale and Norman Yemm, Mallaby was part of what is often considered "the consummate Homicide cast". He also wrote scripts for the series. After Homicide he was an original cast member of The Box in the lead role of television executive Paul Donovan, staying in the role from 1974 until 1975. He was later an original cast member of Cop Shop as head of a suburban police station's Criminal Investigation Branch, Detective Senior Sergeant Glenn Taylor. He continued in that role from the program's November 1977 debut until 1979. In 1980 he appeared in Prisoner for several months as social workerPaul Reid. He also wrote scripts for Prisoner and Matlock Police. He said of scriptwriting that "writing requires a mood. It might be called a creative mood, I suppose. Unfortunately for those close to me, the mood often seems to come around 4 am. I get a spasm of creativity and just have to jump out of bed and start writing". Mallaby also acted in mini-series including Power Without Glory, Sword of Honour and All the Way. He acted in feature films such as Tim Burstall's Eliza Fraser, Petersen, and End Play. During the late 1970s he returned to Britain. There he made appearances in various television series including Secret Army, Survivors and The Professionals, and appeared as a submarine crew member in the James Bond filmThe Spy Who Loved Me. His last regular role was as Colonel Mustard in Cluedo, the "game show-comedy-mystery series''.
Other interests
He also started one of Australia's first hazelnut farms, something he saw as his "basic protection against the insecurity of show business".
