A key parliamentary convention based on trust has been smashed by two Victorian opposition MPs in order to defeat Labor’s controversial plan to make the Country Fire Authority (CFA) volunteer only.

In a day of breaking conventions, the Andrews Labor government made the state’s Legislative Council sit through Thursday night into Good Friday for the first time in history, so two Liberal Upper House MPs, Bernie Finn and Craig Ondarchie, sought to be excused on religious grounds.

They sought “pairs” for their absence, meaning the government also excused two of its own MPs to even up the vote.

The long-standing convention maintains the voting balance when an MP is absent due to illness or other commitments, but now appears to have been destroyed in Victoria after the Coalition hatched a plan to bring the two MPs back for the vote, defeating the bill 19-18 on Good Friday.

Crossbench MP Fiona Patten said it was “the dirtiest political trick I have ever seen in my 20 years around parliaments”.

The government appeared to be trying to take its own political advantage from the illness of another crossbench MP, Rachel Carling-Jenkins, who planned to vote against the CFA changes, but ended up in hospital this week.

The Opposition accused government of refusing to offer her a pair, with Liberal shadow attorney-general John Pesutto accusing the Premier of trying “to seize the opportunity in the most sordid of ways”, but Daniel Andrews denies Carling-Jenkins asked for a pair.

Pesutto said the Opposition’s “leadership group” made the decision to break the pair and turn up for the vote.

“We are proud of what we’ve done in stopping Daniel Andrews’ efforts to try and destroy the great work that CFA volunteers do,” he said.

Opposition leader Matthew Guy also said he was “proud” of what happened.

While the Coalition’s move delivers the Opposition a short-term victory over the government’s controversial fire services bill, which turns the current Metropolitan Fire Brigade into the statewide Fire Rescue Victoria, with paid employees, while the (CFA) becomes a voluntary organisation, it’s likely to have long-term repercussions when MPs are absent.

Labor’s Upper House leader, Gavin Jennings, said the opposition MPs betrayed parliamentary convention.

Trade Minister Philip Dalidakis labelled the incident “Judasgate”.

Former federal Labor MP Dr Craig Emerson hinted at future problems.

In a now deleted Facebook post attempting to explain what happened, Bernie Finn claimed that when he left on Good Friday, he did not plan on coming back, but received a call at 8am on Good Friday asking him to come to the chamber and vote. .

“When I left in the early hours of this morning, I did not anticipate being back this side of Easter,” he posted on Facebook.

“I drove into Parliament, voted, then left,” he wrote.

Finn also wrote “at no time did I ask for a pair”.

Hansard records Finn in the chamber asking for a pair.

Attorney General Martin Pakula called the incident “totally unprecedented”.

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