First, a confession. Michael Palin has long been my hero. About 30 years ago, when I was living in Hampstead, I used to see him most mornings. Not socially, of course. He'd be slogging up Parliament Hill while I was running down on my daily circuit of Hampstead Heath. We never exchanged words (we're both English) but, despite his Ripping Yarns attire and puffed complexion, Palin always smiled.
That was in stark contrast with another celebrity who could also be seen exercising on the heath in those days. Sting, then living in Highgate, had much tighter shorts, the very latest running shoes and a taut physique. But if you tried to make eye contact with this fellow runner, Sting never smiled.
Maybe Sting was worn out by all that tantric sex he boasted about in those days, I suggest to Palin.
''Well, certainly there was no tantric sex in my case and I am still jogging up Parliament Hill,'' he says with a laugh from his home, on the edge of what's arguably London's most beautiful parkland. He's lived in the same house ''for 46 years'', he says before adding: ''No, I've been married for 46 years. We've lived here for 44 years.''
But Palin says he always smiles when he meets other joggers: ''I feel a kindred spirit.''
What makes this anecdote relevant is that Palin's second novel, The Truth, is partly about hero worship, as was his first, Hemingway's Chair, published in 1995.
The protagonist of The Truth is a 56-year-old journeyman journalist, Keith Mabbut, whose literary heroes are George Orwell and Albert Camus. Mabbut is an award-winning writer, too - though a gong from British Gas might be something of a back-handed compliment for an investigative environment reporter.
When we meet Mabbut, his world is disintegrating. His Polish wife, Krysztyna, has left him. His two adult children consider him a loser. And his latest book, an official history of a fictitiously controversial oil terminal on the Isle of Shetland, might possibly attract a larger readership if he could tell the unexpurgated story without being compromised by the need to cash in the cheque from the oil company to pay for his divorce.
Then, suddenly, Mabbut is offered a swan dive of redemption. An unlikely publisher offers Mabbut the chance to profile his own environmental hero, Hamish Melville - a filthy-rich, attention-seeking capitalist-turned-environmental-underground warrior (imagine a cross between Richard Branson and Julian Assange). So now the truth will out …
The Mabbut character came to Palin, he says, when he was walking through Soho four years ago. His first grandchild, Archie, had been born in 2006 (joined now by a brother, Wilbur: ''They have changed my life, significantly'').
After the publication of Hemingway's Chair, he'd spent many years travelling for his popular, laconic BBC travel documentaries, Full Circle, Hemingway Adventure, Sahara, Himalaya and New Europe. But now he wanted to spend time at home. His second novel was long overdue. And for all his many professional guises - comedian, actor, Monty Python legend, film star (A Fish Called Wanda - best supporting actor for a role requiring a chip up each nostril) - TV presenter, non-fiction writer and novelist: ''writing is the thing I enjoy most in any shape or form, even just keeping a morning diary''. (And, yes, with two volumes published so far, the years 2001 until the present day are keenly awaited.)
''I just had this idea of a man, possibly a journalist, who represents incorruptibility,'' Palin says of that stroll through London's most famous red-light district when The Truth was conceived. ''Then, taking it on, we discover he has feet of clay, too.''
The human race should just slow down and think about what it is doing.
About that time, Britain was infuriated by the British parliamentary expenses scandal, he points out: ''A lot of MPs had feathered their nest. They were saying, 'Of course I haven't …' And two weeks later when they'd been caught out: 'No, I shouldn't have done that.'''
By the time the Mabbut and Melville characters were fleshed out, Palin knew his second novel would be an exploration of the phrase ''the truth'', and how it is manipulated in our modern world.
He was just fed up with the seemingly endless exchange of excuses from vocal enemies declaring, 'This is the truth' and 'No, that is the truth', without either side willing to admit they may not be 100 per cent correct.
Fortuitously, Palin's novel is being published at a perfect time - as the British Prime Minister is being grilled about his ''too-close relationship'' with the Murdoch empire, and the Australian Prime Minister struggles under an opinion poll judgment that she lied before the last election.
But Palin says The Truth isn't a moral treatise: ''I wanted the novel to be a good read, entertaining, an interesting story. The Truth is meant to be ironic. But it does dip into areas where we convince ourselves we have done the right thing.
''I wanted to show an idealist, who knows what the truth is, meeting his hero, [someone] who represents everything above common compromise and all that. They get together, and we see how hero worship has always been a dangerous thing. [Melville] has made his own compromises, too.
''The Truth is not meant to preach or point any fingers. It's meant to show that perhaps we should all avoid taking the moral high ground unless we have thought about things a bit more.
''With the media now, the instant impact of news, Twitter, the most important thing is to get your [retaliation] in straight away. People say the most stupid things on the spur of the moment that they then have to retract … The human race should just slow down, think [about] what it is doing, and not pretend that [each individual is] always right.''
His novel roams across many countries, from Scotland and England to India and Brazil, possibly echoing the author's own stamp-encrusted suitcase.
And Mabbut? Or Martin Sproale, the assistant postmaster in Hemingway's Chair, a small man in rural England raging against the coal-black night of corporate rationalisation? Both seem to be polite, mild, unlikely champions. Could they possibly be cast in Palin's own mould?
''Oh dear,'' Palin says after it is pointed out that of the six Pythons (John Cleese, Eric Idle, Terry Jones, Terry Gilliam, the late Graham Chapman and himself) he's the one with whom most sensible people would choose to have a convivial dinner.
''I am by nature conciliatory, I agree with that,'' he says. ''I'm not good at confrontation. I know my strengths. I like company. And I am not a great arguer … I do find it much easier talking to people I like about things we both like.
''And I can't avoid the fact that I have written two novels about characters who question the world as it is. I suppose I do, too. Generally speaking, I enjoy my life. I don't provoke arguments any more than I have to. But I have a stubborn streak. If there are things that are wrong, one has to find a way of addressing them. You can't give a false account of yourself.''
As for the literary heroes who frequent his novels - Hemingway, Orwell and Camus - he has long realised the more you know of a hero, the more frailties they reveal. He admired Hemingway's ''style of writing, his stance, his independence'', for example, long before he realised the author was also ''tetchy, disagreeable, contradictory and dreadful to the women in his life''.
As for Camus, ''he and Sartre shared a mistress … Camus was seen as this exotic Algerian figure, which is exactly the image he wanted. He didn't go to Paris just to write sensitive books.''
Orwell emerges more favourably: ''He was a man of the people who was also an Old Etonian.''
He and the other Pythons rarely meet these days. ''Terry Jones and Terry Gilliam both live very close to me, so I see them regularly. Eric and I met up recently at a social do. John is a tax exile now in Monaco, but we talk.''
Palin will be back in Sydney in September for the joint publication/broadcast of his latest - and possibly last - travel series, Brazil with Michael Palin. ''I had no plans to do another series,'' he says. ''My crew is ageing. But I'd never been to Brazil and it is the size of a continent. [His TV crew] saw it as a fantasy land - sun, sea, sex and samba.''
Was that a true picture? ''There's a bit of sun, sea and samba, but not a great deal of sex,'' Palin says, laughing. ''I missed out again, like Sting with his tantric sex.''
The Truth is published by Weidenfeld & Nicolson, $32.99.