When he finally steps away from politics, senator Ian Macdonald, the former Queensland lawyer turned Howard government minister will have spent more than 30 years in Canberra. The 71-year-old “Father of the Parliament” is currently a government backbencher on around $200,000 a year.

But plans by his boss, Malcolm Turnbull, to cut back on the perks of office, including a “life gold pass”, which gives retired pollies 10 free return domestic flights for two each year at taxpayer expense, have him threatening to cross the floor.

Today in the senate, Macdonald argued that politicians are underpaid and under-appreciated, so it’s up to him to fight for their rights.

“Someone has to start arguing for politicians, arguing for parliamentarians, saying why they’re there,” he said.

“They don’t get particularly well paid.”

MPs earn between $197,000 up to a little over $500,000 as PM. Certainly compared to being paid $5.6 million as CEO of Australia Post, that’s small change. And Macdonald was there when his old boss, John Howard, gave the previously generous superannuation scheme a major haircut 13 years ago under pressure from Mark Latham. Before that moment, politicians were entitled to super, no matter their age, at half their pay after just eight years in parliament. That gave a backbencher $51,000 a year for life.

The Life Gold Pass has been a treasured possession of ex-politicians for nearly a century. It used to be unlimited and changes to it provoked a bipartisan moment last year when four MPs launched a High Court challenge against having their perk trimmed. They lost.

Over the last 15 years, it’s been gradually wound back and the government plans to phase out the Gold Pass altogether in 2020. The Gillard government already killed it off for anyone entering parliament after 2012.

But after 27 years in politics, Macdonald is not prepared to put up with this insult to his sacrifice to public life and will vote against his own party and the government.

“Most parliamentarians, well those on this side, would have done infinitely better financially staying in their legal practice, staying in their business, staying in their veterinary practice, staying in their jobs they had before,” he said.

“But that’s not why they come into this chamber.”

Perhaps sensing the public mood in the wake of losing his health minister, Sussan Ley, after she bought an $800,000 investment property during a taxpayer-funded trip to Queensland, not to mention Bronwyn Bishop’s “choppergate” Malcolm Turnbull has announced changes starting on July 1, to check MP expenses more rigorously.

But it was taking away the life gold pass from a longstanding servants of the people that upset Macdonald.

Concerned about his parliamentary colleagues, he said: “They’re entitled to what was agreed upon in legislation 20 to 30 years ago and it should not be taken from them.”

Invoking an argument Labor used to oppose changes to superannuation by Macdonald’s side of politics last year, the senator said: “No legislation that is retrospective should ever be adopted by this Parliament”.

Despite reducing the offer to 10 business-class fares a year for an MP and their partner, the scheme still costs taxpayers around $1.5 million annually. Since 2001, taxpayers have handed over $17.2 million to fund the Gold Pass.

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