He held positions at Dalgety Farmers Limited, Hawker de Havilland and Australian Aircraft Consortium before entering politics.

On 16 November 2006, Debnam suggested under Parliamentary Privilege that NSW Attorney-General Bob Debus was under investigation by the Police Integrity Commission.

In response, the Government released a police report stating that a minister had been the subject of complaints (not an investigation), and that they were dismissed in 2003 as spurious and groundless.

[4] It was subsequently reported that Debnam's source for the accusation was a convicted child sex offender and bank robber with a history of making unsubstantiated allegations.

[5] Opinion poll support for the Opposition leader declined markedly in the wake of the allegations,[6] which also distracted attention from a campaign against the Government over the sacking of Ministers Milton Orkopoulos and Carl Scully.