Born and raised in Sydney, Dadour served in the Royal Australian Naval Reserve from April 1945 to November 1946.

He then completed a medical degree at the University of Sydney before moving to Perth to start his career as a general practitioner.

He was outspoken in his opposition to the 1979 closure of the Perth–Fremantle railway line by his own party, and in his support for a ban on tobacco advertising.

[1] He then accepted a university offer in exchange for military service,[2] enlisting in the Royal Australian Naval Reserve on 19 April 1945.

[1][3] Dadour was elected to the central ward of the Subiaco City Council on 20 May 1966, replacing the retiring E. Congdon.

[3] In March 1978, Dadour announced that he would not stand for the council election in May due to his increasing workload as a member of parliament and as a councillor.

[5] Dadour stood for the Legislative Assembly (lower house) seat of Subiaco after the incumbent Liberal member Hugh Guthrie announced his retirement.

[6] He was nearly defeated in the 1983 state election after an unfavourable redistribution of his seat's boundaries which removed Shenton Park and added Leederville and Mount Hawthorn.

The City of Nedlands wanted the area between the northern end of Winthrop Avenue and Pelican Point transferred between the two local governments to neaten the boundary.

[9] The Subiaco City Council wanted the Local Government Act to be amended to require a referendum of the affected residents before any boundary changes.

[10] He also revealed a letter written by Premier Tonkin in 1969 showing that he opposed the council mergers back when he was opposition leader.

[13][12] Dadour became known for verbal aggression, which annoyed those within his own party, and which, in June 1973, escalated to him punching Labor MLA Mal Bryce, nineteen years his junior, on the right eyebrow while on a Parliamentary tour in Port Hedland.

[2] In 1979, Court announced that the Perth–Fremantle railway line would be permanently closed and replaced by buses due to low patronage.

[20] In 1980, he threatened to lock National Country Party MLA Bert Crane in his office to prevent him from voting against Dadour's motion calling for the Fremantle line to be reopened, for which the Speaker of the Legislative Assembly rebuked him.

Dadour rode in the driver's cab with Premier Brian Burke and Labor MP Ken McIver on the inaugural train to Subiaco.

[28] In October 1983, Dadour was suspended from the Liberal Party for claiming that some politicians were bribed by the tobacco industry to oppose anti-smoking legislation.

[32] The candidates to succeed Dadour were former federal Liberal member for Perth Ross McLean and future Labor premier Carmen Lawrence.

"[39][40] Dadour's first marriage was to Lesley Joan Clarke, on 18 July 1953 at St Margaret's Church in Nedlands.