Premier Jay Weatherill’s office has confirmed it has been advised the one-time Liberal firebrand passed away.

It’s understood he died in Sydney earlier this week. He was 75.

Lewis was elected to parliament in 1979 as a Liberal, losing his seat of Hammond as an independent in 2006.

But it was in his latter years in politics that he rose to particular prominence.

In 2000, the Liberal Party chose to enter minority government by expelling the turbulent Lewis from its ranks, after repeated public criticisms of the administration and then-Premier John Olsen.

But the decision would come back to haunt it when, in 2002, Lewis was returned as an independent and shocked the state by backing Mike Rann’s Labor to form government in a hung parliament.

The decision saw the Liberals enter a period of Opposition from which they have never returned.

Former Liberal turned independent MP Peter Lewis in the Speaker’s chair.

Lewis had an agreement from Labor to pursue constitutional reform, but his tenure was marked by Question Time spats with Government frontbenchers and ended in consternation, after Lewis and his office volunteers disseminated unsubstantiated allegations of child sexual abuse against prominent public figures.

With a Government no-confidence motion looming, he left the Speaker’s chair, walked across the road to Government House and resigned.

Then-Attorney General Michael Atkinson, who later became one of his successors as Speaker, told InDaily he knew Lewis “very well”.

“During the first term of the Rann Government, I was the ‘Minister for Peter Lewis’,” he remarked.

“And on his day in parliament and in committees, he was the most intelligent and insightful member of parliament.

“He’d probably be remembered for the things that went wrong, more than the things that went right… but he wanted certain things for his electorate, such as a program against [parasitic plants] broomrape and a ban on netting in the River Murray, and he achieved those.”

His successor in Hammond, Liberal Adrian Pederick, said today: “Peter and I didn’t always agree on matters, but he was a long-serving member of the parliament and a long-serving member for Hammond, and my condolences go to his family.”

Lewis said before the 2014 election that he regretted his decision to put Labor into power.

Weatherill said in a statement today Lewis “certainly had an independence of thought and proved to be an effective Speaker”.

“He sat in Parliament for a quarter of a century and led a colourful and at times controversial political career,” he said.

“I extend my sympathies – on behalf of the State Government – to the family and friends of Peter Lewis.”