The former premier fronted the television cameras in Spring Street on Monday morning, announcing he would vacate his spot on the leather green benches and trigger a by-election in his South West Coast electorate.

Unlike the early-evening drama of his ascendancy to the premier's office and the subdued defeat that was 2014 election night, the veteran MP was in a cheery yet reflective mood as he faced the final curtain in the opposition rooms at Parliament House.

In his swansong press conference, Dr Napthine singled out the South West Cancer Care Centre, the region's air ambulance, expansion at the Port of Portland and Princes Highway passing lanes as his local achievements.

Signing the National Disability Insurance Scheme for Victoria was one of his key achievements as premier, he said, while the controversial East West Link was noted down as unfinished business.

"It was a very hard decision," he told The Standard prior to his official announcement.  "I love what I do. I loved every day of being a local member.

"I love constituents coming in with issues - whether it be a housing issue, whether it be an issue in terms of their local business.

"(For instance, I was) out at the Macarthur Bowling Club to talk about toilet facilities at the bowling club. You can't get more down-to-earth than that. I still remember when I was a young member, getting to officially open the new indoor toilets at the Macarthur school. So early in my career I was involved in toilets at Macarthur and towards the end of my career, I'm still involved in toilets at Macarthur."

Denis Vincent Napthine is no stranger to the slings and arrows of outrageous political fortune.

After graduating from the University of Melbourne, he worked for the State Agriculture Department as a veterinarian. The Winchelsea boy was interested in politics from his school days but started to make waves in the Liberal Party when he was working in Hamilton.

Elected as Member for Portland at the 1988 state election, he became Community Services Minister following the 1996 re-election of the Kennett government.

On his 61st birthday he was elevated to the pinnacle of Victorian power. By his 63rd birthday, he was evidently contemplating life beyond Spring Street.

"If I was premier, I would have stayed through," he said. "I would have stayed the full four years if I was re-elected premier. I probably would have served three years as (leader) then stepped down (as premier) and (then) stepped down as (local member) at the 2018 state election.

"In the circumstances, when you go into opposition, it's always a time to rebuild, to re-energise, to redevelop your policies. I think it's in the best interests of south-west Victoria to have someone as a local member who is part of the future rather than someone who is part of the past."

Clear to all was how much Dr Napthine enjoyed being premier. It was a career aspiration he thought had passed him by following his turbulent period as opposition leader, picking up the pieces following Jeff Kennett's departure at the 1999 state election.

The South West Coast MP was satisfied serving as Regional Cities Minister under his mate Ted Baillieu. However, renegade Frankston MP Geoff Shaw precipitated a series of events which resulted in Mr Baillieu tendering his resignation and Dr Napthine heading to Government House for a meeting with Governor Alex Chernov.

"After question time, Ted asked me around to his office," Dr Napthine said. "Now Ted and I are close friends. He said to me that he felt that he had lost the support of the party and that he was going to step down as premier.

"I remember being in his office for several hours that afternoon, urging him to stay on, to talk him out of that position. But Ted was determined. He wasn't demonstrative, but when he made his mind up, he made his mind up. Towards the end of that discussion he said, ‘who should take over?’ and then he virtually said 'would you put your name forward'?"

It was with those few words to his old mate that cemented Dr Napthine's spectacular comeback to the Liberal Party leadership - this time in government.

"And I hadn't even thought about it because I'd expected Ted to continue," he said. "(Ted) said it would be better for him, he would feel comfortable if I took over. At 7 o'clock that night I was elected as leader."

The former vet's appointment resulted in an immediate boost in opinion polls. The flagging Baillieu government was reinvigorated under Dr Napthine's leadership. However, Mr Shaw remained a constant irritant with controversy over the East-West Link and ongoing industrial disputes eroding support ahead of the 2014 state election.

"I firmly believe we were a good government," he said. "I, as premier, gave it my very best shot. I'm particularly proud of what we achieved in that time - whether that be signing the NDIS agreement and getting its headquarters in Geelong, whether it be saving SPC Ardmona (or) the biggest tax change in Victoria's history with the Fire Services Levy, a fair and more equitable property based system, (and) at the same time maintaining a triple-A credit rating."

Dr Napthine has called Port Fairy home in recent times after many years living in Portland. He said he would remain within the region during his retirement.

Many former premiers have been appointed as ambassadors or to other plum roles over the years but Dr Napthine said he had no such ambitions at this time.

"It was an honour and privilege to become premier - one I never thought possible," he said. "I mean, I grew up as one of 10 children on a family farm at Winchelsea and went to the local Winchelsea state school. For somebody from a very humble background, on a farm in country Victoria, to become premier of the state says a lot about our democracy and our political system."