Melissa Lucashenko has the flu but that doesn’t stop her breathing fire down the phone line. “This bloody bullshit about the forgotten white working class – if there’s any forgotten people in Australia, if there’s any battlers in Australia, it’s brown and black people,” she says.

Lucashenko has just found out she’s won the 2019 Miles Franklin award, Australia’s most prestigious prize for fiction, for her novel Too Much Lip. It’s a book the writer says was “risky” from the beginning.

“There’s no point pretending to speak truth to power, you’ve actually got to do it or else undertake another kind of writing,” she tells Guardian Australia. “I was basically terrified for the two years I spent writing this book. But the reception has been a lot more positive than I expected.”

The $60,000 prize was awarded in Sydney on Tuesday night and recognises the novel of “the highest literary merit” that focuses on a phase of Australian life. Too Much Lip, published by University of Queensland Press, was selected from a shortlist including works from the past winner Rodney Hall and a three-time nominee, Gail Jones, alongside Michael Mohammed Ahmed, Jennifer Mills and Gregory Day.

The Miles Franklin was first awarded in 1957 and named for the Australian writer and author of My Brilliant Career, Stella “Miles” Franklin.

“It’s a big deal,” Lucashenko says of her win. “When they told me, it felt as if I hadn’t even been on the shortlist, I was that shocked.” She had previously been longlisted for the Miles Franklin for her novel Mullimbimby in 2014. Too Much Lip was also shortlisted for the 2019 Stella prize.

The novel follows Kerry Salter as she careens into her rural New South Wales home town on a stolen motorbike to see her grandfather before he dies. She doesn’t plan to stay, but then her family – and her country – start to envelop her.

“I wanted to portray the Australian underclass in rural NSW, and especially the black underclass,” Lucashenko says. “I wanted to talk about class. I wanted to write about the connections between poor blacks and poor whites in the country, and in the jail class.”

A founding member of Sisters Inside, the Queensland-based not-for-profit that advocates for the rights of female prisoners, Lucashenko cares passionately about the intersection of the underclasses and the jail system.

“Prison is fundamental to keeping poor people poor,” she says. “The poorest of the poor. Australia hasn’t changed in this respect over two centuries. This mentality of chucking people away when they’re inconvenient started in Britain and has continued until today. Except these days it’s extremely big business.”

Lucashenko started writing Too Much Lip before Donald Trump was elected president of the US. She says she doesn’t agree with the way public discourse since then has reduced discussion of the working class to one of predominantly white men.

“Yes there’s a white underclass in Australia, but there’s an Aboriginal underclass that dwarfs it,” she says. “There’s Asian poor, there’s African poor people, Pacific poor and there’s of course refugee and immigrant poor.”

“The Russians have a saying: the fed don’t understand the hungry. It behooves those of us who are fed to keep that in the front of our minds. I’ve been rich and I’ve been poor, a couple of times each. It fills you with rage to be poor in a rich country and I think that’s perfectly legitimate. We need a revolution.”

Richard Neville, the chair of the Miles Franklin judging panel and Mitchell librarian at State Library of NSW, calls Too Much Lip “a (sometimes) fabulous tale” woven together with “the very real politics of cultural survival” and “a story of hope and redemption for all Australians”.