The opposition Labour Party was quick to recruit her for a campaign against high energy prices. The charity Oxfam just took her to Tanzania to visit one of their projects, and the supermarket chain Sainsbury’s, long partial to featuring celebrity chefs with expensive tastes, picked her for a television piece on how to cook with Christmas leftovers.

But others, on the right, dismiss her as a fake or simply as “The Guardian’s favorite poor person.” In a scathing piece last fall that referred to her as a “poster girl of Welfare Britain,” Richard Littlejohn at the pro-Conservative Daily Mail mocked her kale pesto pasta recipe for 48 pence, about 80 cents, a head.

“You couldn’t make it up,” Mr. Littlejohn wrote. “If I’d set out to compose a spoof Guardian food column aimed at those living in ‘poverty,’ I couldn’t have done any better.”

Ms. Monroe insists that she is “nobody’s paid face.” She turned down a lucrative offer from Tesco, another grocery giant. When the upmarket grocer Waitrose airbrushed out her tattoos in a photo they published with a guest column last year, she posted an indignant comment on Twitter.

She liked Sainsbury’s leftovers campaign, and that is where she has always shopped and priced her recipes, she said. She says she is giving most of her fee to Oxfam, food banks and a local shelter, keeping only $2,600, the equivalent of a living wage for the six-week running time of the campaign.

For all her celebrity, she still lives modestly, keeping to a monthly budget of around $2,000 and trying to save a similar amount. Her benefits were stopped in May when the BBC publicized her book contract, briefly sending her back into a panic because she had yet to receive any money (she has since been paid about $16,500). She says she now earns about $325 a week from her column and freelance writing.

Growing up, Ms. Monroe never thought of herself as poor. Her father was a firefighter, and over the years her parents, who still own a small house in a neighboring town, took in around 80 foster children alongside her and her older brother. She passed the entrance exam for a selective public high school, but struggled there and dropped out when she was 16, working in shops and restaurants until she got a job as an emergency dispatcher, where she eventually made $44,000 a year, just over the average income in Britain.