On Monday night, Q&A's knockout episode for 2016 - and one of its all-time most compelling and emotional outings - came complete with a delightful booby-trap on the dull and winding road on which national debate struggles to find direction. Who knew that Australia had a fearless, fearsome, two-pronged political powerhouse hiding in plain sight for decades?

If only Magda Szubanski and Jimmy Barnes hadn't been busy with other things.

Not that we'd give up those many joys, of course. Let us count the ways. She does gags of the skit and sitcom variety, and much else besides (think Babe; and most recently, an acclaimed book). He does gigs of the sing and scream sort - he's been gargling gravel with singular soul for decades. Showbiz life would normally dictate that this pair would be equally but separately beloved, red-carpet acquaintances with nothing much there to forge a greater bond.

But now we know.

First up, as Szubanski told us: "Jimmy and I are actually family. I'm the godmother of his granddaughter."

A Jimmy-and-Magda family? You could hear Australia pondering how lovely that sounded, and perhaps thinking: count us in.

And then we learnt there is more to the double act than that. Paired on a unity ticket in public debate, they both do Serious, and they do it seriously well. Indeed, if they decided to apply their minds and mettle to it full-time … well, place your bets, people. A politician in a pickle - let's say, as a random example, a Prime Minister with a problematic plebiscite to sell - might find himself asking the question: would I survive an hour in the ring with Jimmy and Magda taking turns to give me a wedgie?

Actually, Malcolm Turnbull, we can answer that for you now.

No, you wouldn't.

The first 15 minutes of Monday's Q&A proved that, as Szubanski and Barnes took it in turns to elucidate their bewilderment with the PM and his plebiscite policy, with a blend of the personal, the practical and the plain obvious. It was arguably the most refreshing debate on same-sex marriage we've seen in … who can recall? A long time. It's been tiresome and turgid for years.

For Szubanski, it's personal, and has been a public concern since she came out in 2012. On the evidence of Monday night, as an advocate and as an explainer she is without peer, given the affection and respect she commands in every corner of the land. She adroitly placed the issue in a budget context - pitting a glorified opinion poll versus money for nurses and teachers. And then she asked us to put ourselves in her shoes.

"Now, Jimmy and I are family. I'm the godmother of his granddaughter. He's a Scottish migrant, I'm a Polish-Scottish migrant. His wife is Thai. I'm a lezzo. We are that modern family ... What threat does it pose except I don't have the same rights as other people?" she asked.

To independent Senator Jacqui Lambie, Szubanski said: "I want to address you on a more personal level. You have an unconventional family yourself, Jacqui."

As a single mother, Lambie would once have been treated terribly.

"That is what is happening to me and my community now."

She spoke of wanting to kill herself as a child.

"I did, when I was 11, 12, 13, and knew that I was gay and this was not going to change and I had no control of it, I knew that it would mean an absolutely terrible life."

And then she asked Nationals Senator Fiona Nash -  the Coalition's plebiscite standard bearer - a stark and simple question: "Do you think I'm equal to you?"

Nash replied: "Of course I do."

Szubanski: "If I was your daughter, and I'm being gay, would you think that I should have the right to be married?"

Nash stumbled, because the question cannot help but prove a slippery slope into weasel words and waffling.

Nash: "I completely respect your view and your desire to see that as equality … "

Szubanski: "But you won't give me my rights. Thanks for nothing."

Ouch. And Magda had Jimmy in her corner all the way: "I don't think we should be spending the money … when there's people sleeping on the streets in Australia, kids that are hungry, there's families that need counselling to deal with domestic violence. All sorts of better ways of spending money than a non-binding plebiscite."

He added: "I don't know if we want to put children and families through this."

It was a raw and gripping debate, and gay marriage was not the whole of it. There was also Barnes' wrenching discussion of the pain of his childhood and the price he'd paid for drinking himself into oblivion as an adult.

His migrant family and their peers "had terrible lives a lot of the time … we were exposed to a lot of violence, alcohol, ignorance, it was horrific stuff".

He has written a book. "I wrote this book to let go of my demons and to open my wounds so I could heal. When I finished writing it I could have ripped it up. I read it and thought there's people going through the exact same things I went through as a child. People in Australia are living this horrific life story."

It would seem clear that Barnes and Szubanski have both arrived at their second act in public life. Both have written books. Both have shared their pain. Both have made their peace. And both are putting Australia on the spot. They've entertained us for years - but are we ready to let them educate us as well?

You wouldn't bet against it. Having walked a long road, these two are not for turning.