But these facts did not deter Mr Randall - at least not initially. A report of a private telephone conversation reveals that about 24 hours after Fairfax Media broke the story of Mr Randall's travel last October - a story which spurred Prime Minister Tony Abbott to tighten rules on MPs' entitlements - the West Australian MP sought official advice on whether he could justify his Cairns trip as ''electorate business''. The call report, obtained by Fairfax Media using freedom of information laws, provides an insight into the impotence of the government body that presides over politicians' entitlements. It shows that on October 17 the Finance Department advised Mr Randall to ''satisfy himself'' his trip to Cairns constituted ''electorate business''. ''It remains up to Mr Randall to satisfy himself that his use of the travel and TA is within entitlements, and would be defensible as electorate business,'' states the report of the phone call between the Finance Department and Mr Randall's office.

''I can't provide definitive advice on whether it was or wasn't electorate business. I noted that the claim was made for electorate business outside of the electorate, so [Mr Randall] needs to be satisfied the purpose of the travel and discussions related back to electorate business.'' The phone call report provides another example of the Finance Department's incapacity or unwillingness to cast judgment on politicians' questionable expenses. Previously, Finance claimed it was ''not possible to determine'' whether Mr Abbott's travel to the wedding of then parliamentary colleague Sophie Mirabella was correctly charged to taxpayers as ''official business''. It also highlights the problems that arise when an ''honesty system'' is used to police MPs' entitlements. Senior Coalition MPs privately regard Mr Randall's travel to Cairns as the most egregious episode from the expenses scandal late last year. Even Mr Randall decided the travel was not defensible.

Following intense media scrutiny he refunded taxpayers the $5285 he and his wife spent on the Cairns trip. Expense records show Mr Randall and his wife flew to Cairns for an overnight stay in November 2012. The MP claimed the trip was ''electorate business'' despite refusing more than eight times to say what business he was doing there. Five months have passed since the original story broke and the MP has still not explained how the trip benefited his constituents. Following stories by Fairfax Media, Mr Randall refunded taxpayers and resigned from the parliamentary committee overseeing MPs' privileges and interests. He eventually explained the reason for the trip was to meet the then opposition whip Warren Entsch ''for a couple of hours''. Mr Randall said taking a ''look'' at his investment property was a secondary priority and ''it wasn't as if I got the keys or anything''.

Mr Randall told Finance the day after the original story broke, on October 17, that he had flown to Cairns for ''important discussions'' with Mr Entsch, the call report shows. But the report contains nothing suggesting how these ''important discussions'' related to Mr Randall's electorate. Follow us on Twitter