McDonald was in The Aunty Jack Show between 1973 and 1975, in various interpretations of The Norman Gunston Show between 1975 and 1881, and played hapless Arthur Beare in Mother and Son between 1984 and 1994. He also embodies, in the memory of Australians, the archetype of the clown-who's-crying-inside after suffering a breakdown while attempting to revive The Norman Gunston Show in 1993, and seeking treatment for depression and anxiety.

So it's hardly surprising that McDonald was one of the first icons asked by the ABC to analyse the nature of Australian comedy in Stop Laughing ... this is serious, a documentary series that starts on Wednesday. He joins the likes of Barry Humphries, Magda Szubanski, Tim Minchin, Paul Hogan and Shane Jacobson in trying to figure out whether we laugh differently from other nations.

What McDonald brings to his comic performances is a poignancy that suggests tragedy is never far away. That was apparent even in our conversation during the week, when McDonald told an anecdote to explain why Australians are unlikely ever to see him in a comedy again, because he is going deaf. He was discussing his latest (and probably last) project – an American drama filmed in Tasmania, called The Light Between Oceans.

The writer-director, Derek Cianfrance, likes his actors to improvise around the basic script, and in one scene, McDonald was playing a father interrogating a young man (played by Michael Fassbender) who is interested in taking his daughter out.

"My daughter ends the scene by saying 'He's taking me on a picnic tomorrow'. I think, 'I'd better say something here". So I say, 'A picnic? Where are you taking her?' Michael ad-libs, 'I thought we'd go to the cemetery.' I say, 'I don't think that's really appropriate'.

"Then we stop and do the scene again, and I say, 'A picnic? Where are you thinking of taking her?' This time he says, 'The abattoir'. I say, 'Why on earth would you be taking my daughter to an abattoir?' Then I thought he said, 'For the embryos'. I had to think of a reply. So I said, 'Embryos? Embryos? Veal is not a popular meat in this country.' Michael didn't know what was going on. He told me later what he actually said to me was, 'For the ambience'. Jesus. I wasn't playing a deaf man. I thought, 'This is no good, I can't do this, this is too hard'."

That kind of experience makes McDonald laugh but also convinces him he was right to retire to his farm near the NSW town of Berry. When I ask what his next project will be, he replies: "Lots of fishing and gardening. I'm serious. It would have to be something pretty bloody exciting to make me want to go back to work."

It will be a loss to the nation.

Stop Laughing ... this is serious starts on ABC1 on Wednesday, March 25, at 9pm.

A life of laughs

Garry McDonald decided comedy was his career back in 1968 when he was 19 and appearing as an ocker in a blue singlet in a stage revue called Terror Australis. It had received bad reviews, but the Nobel-prize winning author Patrick White wrote a letter to The Sydney Morning Herald saying it was the funniest show he'd seen in Australia.

McDonald's big TV break came in 1972, when Graham Bond joined the cast of Aunty Jack and handed him a sketch titled What's On In Wollongong. "It was full of alliteration, and we thought it would be funny to do it with a really flat voice," he says. "I just wanted the character to have a protruding mandible, but Graham and I used to try to one-up each other, trying to make each other laugh. On the day, I thought shaving cuts would be appropriate for a television presenter and the comb-over hair was because I was obsessed with going bald. I think there was a dry cleaning tag on the suit, and I said, 'leave it there'."

And so Norman Gunston was born. He went on to be the only fictitious character to win a Gold Logie, and to curse McDonald's life.

Although Gunston's bizarre interviews with unwitting celebrities looked as if McDonald was a brilliant ad-libber, he was actually working most of the time from a script developed by his co-writer, Bill Harding, who had a knack of anticipating how the celebrities would respond to very dumb questions.

"Bill's material was hysterical, I used to work my arse off so that I could get his lines in. It was extraordinarily full-on. I can't believe I even agreed to have another crack at it in the '90s. I must have been mad. It's a young man's game, that sort of thing."

Does he use the term "breakdown" for what happened in 1993, when he had to cancel the revived Gunston show after two episodes? "Yeah, oh yeah. I really got back on track once I went to the St Vincent's Anxiety Disorders Clinic. Once I went there and had cognitive behaviour therapy, that was the road back. It took a year or two to be really strong."

The experience, though painful, helped him to add depth to his character of Arthur in Mother and Son. In revues, he'd been "very broad" but "I learned I didn't have to do that much".

But back to the subject of the documentary Stop Laughing ... this is serious: our sense of humour. Australians love satire, McDonald says, but not when satirists put themselves above their victims. That was the secret of Norman Gunston: he mocked his guests but mocked himself just as much. There was an innocence in Gunston that made him more than a slapstick clown.

"It was taking people down a peg, tapping into that tall poppy thing that is very Australian. We're an egalitarian society. But Norman is so naive and so ignorant, he's not nasty. That's what people liked."

A fish out of water
London's main fish market is Billingsgate, and 70-year-old Roger Barton has worked there for 55 years, taking only five weeks' holiday in all that time. He is known as "The Bastard of Billingsgate" because of the ruthless way he makes his deals and drives his 13 employees.

This is why Barton has to be a bastard: "There's an old saying: 'There's more sharks in Billingsgate than there is in the bloody Mediterranean.' Most people don't last more than two months. Imagine you've got to get out of your bed every morning at 1 o'clock. Most people are just coming home from the pub. If you work in Billingsgate, you've got to be in bed by 6 or 7 o'clock, so you can get some kind of sleep. You've got to be sharp, prepared and ready."

The BBC decided to see if the skills Barton has developed in 55 years are transportable to other environments, and took him to New York, Mexico City and New Delhi to make a three-part documentary called World's Greatest Food Markets (showing on SBS on Thursday).

But as soon as they arrived in New York, the BBC encountered a problem: The lion turned into a lamb. Director Jamie Balment reported: "For the first few days of filming, 'The Bastard' went into hiding: Roger was nice. The combination of representing the BBC and seeing himself as a guest in a foreign land turned him from Kray twin into Attenborough. So [co-director] Will Lorimer and I turned bastards ourselves, and after a blunt chat, the old rogue reappeared."

Barton laughed when I read him that, and said the directors had not understood his tactics. "Wherever you go in life, you can't expect people to welcome you into their environment and make it easy for you. When you first meet people, if you're going to learn from them, you have to smile and shake hands. If you find they can be difficult, then the gloves have to come off, you have to put them in their place. You do have to flex your muscles. So bring on a bit of the English bulldog spirit – we never won two world wars by running away. Roll up your sleeves and let's see how good you are. I think I did quite well for the country and for myself."

Barton found some of his competitors in the markets of New York and Mexico were even more ruthless than he is, but he got a shock in Delhi. "It was an eye-opener. I saw a different culture, different people. I'm not religious, but I was quite humbled by them.

"When you've been brought up in the environment that I have, it's very hard to let the reins go. It's the only way you know to trade. You have to be mean, you have to be tough, otherwise you'd be bottom of the sandcastle all your life.

"In India, they're quite happy to get a living. They don't want to drive around in a Rolls-Royce. They don't want a big mansion.

"In England, if they've got you on the floor, brother, look out because they will put the boot in. They're relentless. Some of the people in Billingsgate ought to go to India. They might find there's other things in life besides being the top brick on the chimney."

The kindness of the marketers in Delhi made him reflect on his life, and how his devotion to work had cost him two marriages.

"Both wives said, 'You're not married to me, you're married to Billingsgate fish market'," Barton admits. "I wish I'd have had the brains to have more understanding, and more time for my wives.

"It's difficult to be devoted to a business and devoted to a woman. It's heartbreaking and you take it to the grave with you."

So if he was mellowed out by the Indian experience, did that mean he'd lost his edge when he got back to Billingsgate? "I might have done for one day, but I soon come back to earth with a bang. If I hadn't have done, I'd have starved to death, because these are mean bastards, they'll eat you alive."
 
World's Greatest Food Markets starts on SBS on Thursday, March 26, at 8.30pm.

For more, go to smh.com.au/entertainment/blog/the-tribal-mind.