Author Kathy Lette on her new book

Australian author Kathy Lette. Picture: Daniel Hambury

Whatever, when we meet for tea at the Savoy (her treat, she used to be writer-in-residence at the London hotel) the 55-year-old Australian novelist is a complete delight.

She is game, gossipy, knows absolutely everyone, and beneath the blizzard of flip Antipodean banter is undoubtedly A Good Thing. Witness her latest book, Courting Trouble, which is as full of quips as previous works Mad Cows and Foetal Attraction but also promotes a feminist message.

The book is part legal thriller, part romance, part frontline report from the battle for equality. Its heroine – leggy chocaholic barrister Matilda Devine – is left by her husband and fired from her chambers. So she moves in and joins forces with her brash Aussie solicitor mother to prosecute women’s causes. It’s Ab Fab meets The Accused, and the first in a planned series: the TV rights are already sold.

Australian author Kathy Lette (C) poses with her husband Geoffrey Robertson (R) and their daughter Georgie. Picture: Getty

“Feminism is in the zeitgeist again, thank goodness,” Lette says. “There’s a real resurgence among young women – the Everyday Sexism project, Caitlin Moran, Lena Dunham – which is so exciting. Finally it’s fashionable to be a feminist, and especially a funny feminist.” Though Lette thinks some things have gone backwards for women. Apart from female genital mutilation and kidnapping in the wider world, at home women still earn less, carry the burden of childcare and worse.

“The Twitter trolling last year [of the currency campaigner Caroline Criado-Perez and others] was devastating – the level of misogyny underneath the surface,” Lette says. “I also wanted to write about the brutal cross-examination of women in rape trials.”

The book details the use of the internet for abuse and coercion and contains some shocking courtroom dialogue. “Every line you read in the book was taken verbatim from trials. It’s horrific.”

Lette’s machine-gun punning has obscured the fact that she has always talked about serious issues. Her first novel, 1979’s Puberty Blues, described what it was like to grow up as a smart, sassy girl amid the neolithic surf hunks of the Sydney suburbs, where “Germaine Greer” was rhyming slang for beer. The book propelled her into a career as a newspaper columnist and sitcom writer. In her last book, The Boy Who Fell to Earth, she detailed – with his permission – what it’s like to be the mother of her son Julius, 23, who has Asperger’s syndrome.

“That was the most serious, heartfelt book I have ever written,” she says. “I just dipped my pen into my artery. And it worked. The critics asked why I tried to be funny, but anyone with a kid with special needs knows that the only thing that keeps you going is a black sense of humour.”

She gets lots of grateful mail from parents in similar situations and has become a spokesperson for autism charities.

It’s surprising Lette has never set a novel in the legal world before. Her husband – the father of Julius and of their daughter Georgina, 21 (just graduated with a double-first, Lette proudly tells me) – is the leading human rights barrister and author Geoffrey Robertson.

A fellow Australian, Robertson was John Mortimer’s deputy on the Oz trial in 1970 and more recently defended Julian Assange. She says it’s awful being married to a human rights QC “because they are always working, 24/7, for nothing – my two least favourite words are ‘pro’ and ‘bono’ – and you can never get the moral high ground”.

Helen Fielding made Bridget Jones’ boyfriend Mark Darcy a human rights lawyer after hearing Lette describe their life. Lette and Robertson met in 1988 on an episode of his TV show Hypotheticals. “Can you imagine what it’s like to have live footage of yourself falling in love?” giggles Lette. “I can see myself flirting with him. My eyelash-batting average was higher than Allan Border’s. Women are aroused by intellect and I had never met anyone like him before.”

They talked till 2am and he proposed two weeks later, their whirlwind romance only slightly impeded by the fact she was married to Australian TV executive Kim Williams at the time and Robertson was dating Nigella Lawson. “When I first moved here there was a lot of hostility in the press,” she says. “The gist of it was: how could this handsome QC break up with this gorgeous domestic goddess, the daughter of the Chancellor of the Exchequer, for a loud-mouthed colonial nymphomaniac.

“I’m like: how dare they call me a loudmouth? It was a different world in 1988. People would hear my Australian accent and their nostrils would go up in the air. I really didn’t know whether I’d survive.”

Today, Lette is a fully fledged member of the liberal Establishment and really does seem to know everyone. She knew she’d been fully accepted into English society when she was asked to present polo cups, and a kiss, to Princes William and Harry two years ago: she asked William if he wanted tongues. “English people compartmentalise because of the class system, whereas Australians are used to mixing in,” she says. “I can go from tea at Buckingham Palace to beers with single mums on a council estate with ease. It’s like being coated in Vaseline.”

Courting Trouble is dedicated to her best friend, Helena Kennedy QC, and she has a posse of gal pals she calls her Wonderbras, because they support each other and make each other look bigger and better: Ruby Wax, Maureen Lipman, Sandi Toksvig, Jo Brand and Ronni Ancona.

She has persuaded other chums – Mark Haddon, Stephen Fry, David Hare – to name villains in their next works after Lord Chancellor Chris Grayling, as she did in Courting Trouble, so incensed was she at his planned ban on books for prisoners (“I’m from convict stock”).

There’s a rather more appealing figure looming over our conversation. Robertson’s junior counsel in the Assange case was Amal Alamuddin, the British-Lebanese barrister who is due to marry George Clooney.

“He’s lucky to have her,” says Lette bluntly. “She’s not only incredibly brainy and beautiful; she’s really kind, very funny, deliciously self-deprecating. If I looked like her I’d have love-bites on my mirror, but she doesn’t have any vanity about her. They are both passionate about human rights. She has an idiosyncratic, quirky style all her own and is a real woman’s woman. When Georgie got her results, we had tea with Amal afterwards, and she was so kind.”

Lette and Robertson are not going to the wedding but have been invited out to Lake Como afterwards, and she is sworn to secrecy about the dress, the ceremony, etc. Was she star-struck when she learned her friend was marrying a film god? Of course not.

“I knew him a long time ago, back in 1987,” says Lette. “He was an actor on the show I was writing in America, The Facts of Life. I didn’t spot that he was gonna be famous; I just wished he’d shave off those sideburns.”

The prospect of a scoop looms, Lette having told me earlier that in Australia two women who have slept with the same man will bond over it. I don’t suppose, I say, that you and gorgeous George ever…

“I wish!” she yelps. “He did ask me for coffee once and I said no. ‘You’re an actor, you put other people’s words in your mouth and you don’t know where they’ve been!’” Lette pulls a clownishly tragic face. “Imagine how much I regret that now!”

• Courting Trouble is out now, published by Bantam Press, £14.99 in hardback, £8.49, e-book.