Energy News spoke yesterday to Vicki Tinley, who is first fill spares and inventory manager at Chevron in Perth, but she was not inclined to comment on the matter.
She was formerly material operations advisor at Chevron Australia.
Tinley was named as mines and petroleum minister last Thursday but was stripped of the role just three business days later due to what McGowan called "conflict of interest" issues.
DMP acting director general Dr Tim Griffin had not even had the chance to meet Tinley yet, Energy News learned, though the department is still waiting on the state government to appoint someone permanently after Richard Sellers accepted the same role with the Department of Transport last year.
The former Liberal government halted the process of looking for a permanent replacement for Sellers knowing the election was coming up and would not be able to finish it in time.
Industry now has arguably a better-known entity to deal with in the Canberra-born Johnston, who was shadow minister for mines and petroleum for eight years and shadow minister for state development from 2012-2015.
"Minister Bill Johnston will take on the Mines and Petroleum portfolio, after it became apparent that Minister Peter Tinley would need to manage a potential or perceived conflict of interest in that portfolio," McGowan's office said in a statement yesterday.
McGowan said his Cabinet was only made aware at its first meeting that one of Tinley's family members worked in the oil and gas industry.
The ministerial changes will be formalised later this week.
McGowan called the move a "responsible change" to state cabinet to ensure ministers can do their job without any conflicts, potential or perceived.
"Once cabinet was made aware of the potential conflict it soon became clear that managing the issue would be too complex, given the portfolio responsibilities and therefore the matter was dealt with at the earliest opportunity," he said.
"Although the conflict could have been managed in an appropriate manner, I have made the decision to put the issue beyond any doubt."
Peter Tinley, who has been touted as a future leader of the WA ALP, has held portfolios involving housing, jobs, science, Asian engagement, the Gascoyne and the Goldfields.
He will return to the housing portfolio which he quit in late 2012 after the expected "personal upheaval" as a result of his family's involvement with Port Village Accommodation which BHP Billiton had placed into receivership.
McGowan handed Johnston the housing portfolio as a result of Tinley's decision at the time.