Cait Reilly bats off accusations that she is little more than a "job snob", as the work and pensions secretary Iain Duncan Smith once branded her. She is currently working on the checkout in Morrisons. And she is no scrounger. "I hated being on benefits," she said.

What roused the 24-year-old geology graduate, a self-described reticent and shy woman, who likes to "keep herself to herself", was her Jobcentre telling her that she could no longer do her work experience in her local museum.

Instead, she was told that she had to do unpaid work stacking shelves in Poundland.

"My first reaction was to be really upset because I loved going in there. They [the museum] depended upon me quite a lot and I depended on them for the experience.

"And then it was a feeling of frustration because it didn't make any sense," she said of having to trade one unpaid placement, which she was personally gaining from, to stacking shelves in Poundland – something she had already had plenty of practice doing.

Her Jobcentre managers, she said, "knew I was doing the work experience ... they knew I wanted to go into museum work and they just said, 'you've got to do it, you've got no choice ... it's mandatory.'"

After coming to the Guardian with her story, the solicitors Public Interest Lawyers offered to take up her case pro-bono.

What the courts decided was that people such as Reilly simply were not given any guidance about what they were entitled to do or not do.

In fact, despite being threatened with sanctions, her placement in Poundland was not mandatory at all. But no one seemed to know the rules – they were not even set out in public documents.

"That just shows how ridiculous these regulations are and how hard it is to understand. Whether it is the people being put on them or the people who are putting them into place, no one can interpret them properly ... Frustrating is the best word for the whole thing," she said. "It seems a bit scary [the government] are able to do that."

Reilly's battle against the Department for Work and Pensions so-called "workfare" schemes hit the headlines in January 2012 just as ministers were themselves dealing with a series of protests from the public and from major corporations such as Waterstones and TK Maxx.

As high street chains dropped out one by one from the DWP's work experience scheme, fearing they would be linked to exploiting the unemployed for free labour, it was Reilly who became the lightning rod for a debate on the poor and undeserving poor.

Reilly, who has no party political allegiance, said that after various columnists, pundits and government ministers besmirched her work ethic she found it difficult to keep her cool.

"I was angry. We're the people they're meant to be helping. We depend on them for the system to help us get out of the system, if that makes sense. I didn't want to be on benefits. I hated it. I wanted to get a job as soon as I could. So for them someone as high profile as that to say, "well they're not trying, they're a job snob, they're lazy, they're a scrounger ... It really made me angry."

She says after that episode she retreated into herself, buoyed only by her family and letters of public support that would arrive for her at the museum. "It's easier to be quiet and angry ... I knew it would cause a hell of a lot more problems if I spoke out. [And] that's not really me."

And what about Poundland? After fighting her case for just over a year, she admits she still shops there. "I'm not going to lie ... They do some great bargains."