Hester Stewart died in April
Maryon Stewart's 21-year-old daughter Hester died in April after taking the legal party drug GBL.
In her first broadcast interview, Maryon talks to BBC Radio 5 Live's Victoria Derbyshire show about her mission to ban the drug, ahead of a meeting with the Home Secretary tomorrow.
Hester Stewart was a medical student with a promising future.
"She was just a model daughter," says Maryon.
"She was a great deal of fun, she was a great friend, she lit up the room when she walked in".
Maryon believes that Hester would not have taken a drug she knew might have potentially deadly consequences:
"Hester wasn't the kind of person who would have taken cocaine or heroin.
"If she knew something was dangerous, she would never have done it."
GBL (gamma-butyrolactone) is a colourless, odourless liquid - developed as an industrial solvent - which can give users an intense high when taken in small doses.
It is similar to the banned "date-rape" drug GHB, and converts into that substance in the stomach, which can be lethal in tiny doses when mixed with alcohol.
You don't expect to take two legal things like alcohol and a natural high, and end up in a coffin"
"As somebody said to me", Maryon told Victoria Derbyshire, "you don't expect to take two legal things like alcohol and a natural high, and end up in a coffin."
Maryon said she was concerned about how some people saw taking legal highs as harmless as "eating smarties".
"There are so many of these legal highs on the market that are marketed as herbal and safe.
"I think it's so awful that we're actually letting young people be subjected to this illusion that they can take these things and they're safe".
Last summer, the Advisory Council on the Misuse of Drugs advised that GBL should become a class C drug, but no change has yet come about.
Maryon said she couldn't believe that the drug was still legal.
"I'd like to know: why the inactivity?
"Because it's actually cost my daughter's life, and, for goodness' sake, after my daughter was planning to save lives in her career, well, she'd want me to be doing this now so that we can avoid any further disasters."
She said that she was "hopeful" about her meeting with Health Secretary Alan Johnson on Wednesday.
"He's a father, he's got four children, he was the minister for health.
"I think he's probably got a really good appreciation of what's going on out there".
Maryon said she felt it ultimately came down to education and raising awareness.
"I don't think it's a five-minute thing," she said.
"I think it's going to take some time."