Opposition leader Mark McGowan has called for an open, independent inquiry into Troy Buswell’s traffic incident “so the public can have confidence criminality is not being covered up”.

Mr McGowan said he simply did not believe that Premier Colin Barnett’s top two advisers did not ask Mr Buswell’s chief-of-staff questions about what preceded the former treasurer’s breakdown when the trio met on February 25 for 45 minutes.

The Legislative Council was told yesterday that during the meeting, Mr Buswell’s chief-of-staff Rachael Turnseck told Brian Pontifex and Narelle Cant from the Premier’s office that she had been at the Kings Park wedding the former treasurer attended before he drove home and crashed his ministerial car early on February 23.

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The following day - Monday, February 24 - Ms Turnseck told Mr Barnett that Mr Buswell had suffered a breakdown but did not tell him about the traffic incident, despite knowing about it.

Mr Barnett has said neither he nor his office found out about the traffic incident until Sunday March 9 following media queries from The West Australian and Channel 7.

The Premier told the Upper House yesterday that Ms Turnseck “left the reception independently and earlier in the evening”.

But Mr McGowan said it was clear huge amounts of alcohol had been consumed at the wedding and Ms Turnseck knew about Mr Buswell’s crash.

“If she was at the wedding and she advised Mr Barnett’s most senior advisers of that, what did they ask her about those events,” Mr McGowan said.

“I find it inconceivable that they would not have asked what happened on that night.

“I think there is enough evidence now for an independent inquiry into these matters so the public can have confidence that criminality is not being covered up and I reiterate, driving whilst extremely intoxicated is inexcusable under any circumstances.”

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Mr McGowan said Ms Turnseck had an obligation to tell the Premier or his staff about the traffic incident.

“If you know about a serious crime that endangers lives then you should tell people,” he said.

Mr McGowan said the inquiry could take the form of a parliamentary or judicial inquiry.

“The inquiry needs to look at who knew about this inside the most senior levels of the Government, when they knew and perhaps why were the right questions not asked by the Premier,” he said.

He also called for “clarification” surrounding a claim by Police Commissioner Karl O’Callaghan that there was no prospect of proving drink driving charges in the absence of a breath test of Mr Buswell on the night of the crash.

“I’ve had people advising me, who are lawyers, who say these things can be prosecuted,” Mr McGowan said.

“In fact I think I was advised this morning that (Perth QC) Tom Percy said that they can be prosecuted, so I think perhaps that needs further examination.”

Mr McGowan said the police side of the affair should be allowed to run its course until complete, but the independent inquiry’s terms of reference could be widened later to examine the police response if necessary.

Mr O’Callaghan said a police inquiry was progressing but officers from the major crash squad would not interview possible witnesses until they had completed a forensic investigation.

Four cars were damaged in West Perth and Subiaco on the night of the wedding but police were yet to determine if Mr Buswell's car was involved in any of the incidents.

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