Premier Colin Barnett said today he was not surprised by Troy Buswell's resignation.
The former treasurer saw the Premier yesterday and told him he was resigning immediately.
Mr Barnett told ABC radio this morning that Mr Buswell was very emotional yesterday.
"I had expected it (the resignation) for some time," Mr Barnett said, but that he thought it would be at the end of the year.
"I think he showed courage. I think he did it in a very dignified way."
Mr Barnett said he told Mr Buswell that history would be kinder to him.
The Premier said no-one excused Mr Buswell's behaviour.
He said that as a minister Mr Buswell had done nothing wrong but that it was his personal conduct that was the problem.
"The advice of his doctors was that he should stay where he was for a while and he has improved but I thought that he probably would have resigned certainly by the end of the year," Mr Barnett told ABC Radio.
"No-one excuses his actions but as I said to Troy yesterday, 'I think history will be kinder to you than it is now'.
"If you look back at Troy's efforts as a minister he did nothing wrong in that role.
"It was his personal conduct and when you are in public office your are accountable for that.
"That personal conduct let him down.
"But if there was a job to be done you could give it to Troy and it would be done.
"Many who didn't know Troy would have seen him in the worst light.
"Troy was a gentle person. It may sound strange to say that but one of the reasons he was popular in his electorate is that he would help someone who is in strife, having problems in their family and that is a side of Troy that people who are close to him did see.
"He would look after the underdog: very caring, very passionate.
"But you are a public person 24 hours and in Troy's case, some of his antics became national, if not international news.
"He is a bit of a larrikin, that's why people like him, but he was also a complex personality.
"What Troy did yesterday was very dignified and I think he showed courage. He explained his health condition and explained he could not continue in public life in a very dignified way."