Though he insisted from the start there would be no wrecking or undermining, ex-prime minister Tony Abbott has twice now crossed the line from legacy protection to vindictiveness, writes Barrie Cassidy.

Have you noticed what's gone missing? Seemingly dead, buried and cremated?

Those interminable doorstops at a factory within easy driving distance from Parliament House that usually involved the prime minister putting on a hard hat and mouthing vacuous slogans.

They happened almost every day and rarely did they advance the national interest one inch. Instead, they simply served as fodder to the meaningless, mindless political argument du jour.

Kevin Rudd started the habit, Julia Gillard copied him, Tony Abbott turned it into an art form, and Bill Shorten felt the need to keep up, or lose.

So far at least Malcolm Turnbull has eschewed the practice, preferring to face the media less often, but in a more mature way when he does.

Sorry, this video has expired Barrie Cassidy dissects the week in federal politics

Neither is Turnbull doing most of those long form interviews with cringingly supportive mates who never test or genuinely inquire, but rather advocate for their own precious narrow causes.

So some things have changed. And the way the prime minister of the day deals with the media, and through them, the public, is important.

But even more important, of course, is policy, rhetoric and direction.

Paul Keating once said that when you change the government, you change the country. The question now is whether changing prime ministers is akin to changing the government.

Even if you argue it's not - by a long shot - it does imply change nevertheless, and that's where Tony Abbott's self-indulgent farewell radio tour comes in.

Though he insisted from the start there would be no wrecking or undermining, he has twice now - with Ray Hadley and Neil Mitchell - crossed the line from legacy protection to vindictiveness.

On the leadership change:

We did what we said we would never do.

On reports that members are resigning from the Liberal Party:

I can understand why a lot of people feel bruised...

(No matter that other reports suggest that for every member resigning, a new one is signing up.)

On whether he can forgive Malcolm Turnbull:

I might exercise the former prime minister's prerogative of silence... there has been a lot of dirty water under the bridge...

And on Turnbull's recent past:

Malcolm didn't stay in the Parliament to be somebody else's minister.

That, by the way, was only the second time in two interviews that Abbott referred to the Prime Minister by name.

So much of that can and will be dismissed by his supporters as a basic reflection on the brutality of politics. More damaging to the Coalition and Turnbull is his insistence that policies have not and must not change; that Turnbull can do his media differently, but the core principles that he (Abbott) espoused must stay the same.

That is unrealistic. Simply changing a junior minister in government changes perspective, emphasis and ultimately policies. They never stay the same.

Yet Abbott has signalled that when they change, he will be on the attack.

The first example was the ditching of the higher education reforms. At the first opportunity, Abbott expressed his disappointment, and then followed up by suggesting his first budget wasn't so bad after all, just "too gutsy for the parliament we had".

And then a warning shot on taxation reform - that to increase the rate of the GST would be "a terrible mistake".

So there you have it all laid out. Tony Abbott is going to act as a conscience for the party's right, prepared to be publicly critical of policy changes whenever those changes offend him.

He won't be changing sides ("The last thing we need is another conservative party, particularly a rogue conservative party that is raging against the world") but he will be a thorn in the party's side if it tries to move away from his legacy.

That spells trouble for Turnbull.

The new Prime Minister says everything is now on the table. That's a sensible beginning to any discussion. Turnbull is simply saying he's open, as he should be, to new ideas. He should be able to refresh and modernise without a former prime minister sniping from the backbench.

Abbott was asked by Neil Mitchell whether Turnbull could be a great prime minister. Abbott said that everyone "can grasp greatness", and that growing in the role is the key.

The same advice applies to the role of ex-leaders. Some take it, some don't.

Much of this might wash over Turnbull. Abbott is the darling of the right, but he doesn't have the residual community support that even Kevin Rudd had when he was deposed.

But over time this stuff can hurt, especially if the election is tight.

The cliché goes that "time heals all wounds". Others have argued that it's what you do with the time that heals.

Let's see what Tony Abbott continues to do with his time.

Barrie Cassidy is the presenter of the ABC program Insiders. He writes a weekly column for The Drum.