Eventually not enough evidence was found to identify the leaker who Mr Lloyd said had flagrantly breached the Australian public service code of conduct. Public Service Commissioner John Lloyd has championed the highly politicised construction watchdog. Credit:Jay Cronan In an answer to a question on notice lodged by Labor senator Joe Ludwig, the APSC said the estimated expense of the investigation represented the salary costs of the staff member who did the inquiry. If it was one person conducting the inquiry, as suggested by the APSC's answer, then it appears as though it was at least a months' work for a senior staff member. The commission advised ministers' offices at least twice that data used to bolster their argument – that diggers' pay was "catching up" with that of public servants – did not support the claim.

After the story was published in March Public Service Commissioner John Lloyd said he would launch an investigation to find out where the leak came from. At the time Mr Lloyd said leaking "lets down people who are conscientious and do the right thing". "If you know someone who has leaked anything you'll never trust them," he said in recent months. The Australian Public Service Commission is a central agency that plays a huge role in influencing the culture and direction of the federal bureaucracy and one of its important jobs is to promote adherence to the APS code of conduct. Not investigating the leak may have been seen by some within the bureaucracy as setting a bad example.

The APS code of conduct says public servants must maintain appropriate confidentiality about dealings with any minister or minister's member of staff. But it appears there would be few options for a public servant to safely blow the whistle on politicians using incorrect information. Anybody who leaked information about how information was used by politicians would not have their issues investigated by the Public Interest Disclosure Act 2013 - a point previously made by investigative journalist Andrew Fowler. As Mr Fowler wrote in an article for the The Interpreter a year ago: "And herein lies the flaw of a procedure which threatens public servants with jail for releasing information to the media. "The public service whistleblowing rules are simply designed to rigidly enforce the Australian public service code of conduct.