She said children were genuinely excited about writing a poem during one of her on-site events.
"Your imagination is huge and you can lay in bed and travel to all sorts of places and think about things whereas you can't do them," she said."That's one of the questions I would think - 'where would I be if I could?'"
For Ms Larkman, the answer is always watching the hustle and bustle of London's Victoria Station from the top of the escalators on the way to visit her sister, but for others it was as simple as being able to see their children on the swings at the park."During this project I have met so many other people trying to manage what is essentially a fluctuating condition and also the shock of realising how bad ME is," she said."You just don't see people who are bed-bound, or who are on oxygen, and because you don't see them, even though I'd had it for years, it's been a real revelation."
Some participants were unable to speak to record their messages, so wrote them down or sent them by text, but others were determined to be heard."We extended the project for a month because people wanted to wait for that day when they could send a message," Ms Larkman said.
"Knowing how important it is for people to have their voice heard in these places, it feels like a real responsibility."
People who enter the box are invited to write a postcard to the person who recorded a message they listened to.She said if someone were to tell her childhood self that she could go somewhere and meet writers, breathe the same air as Jacqueline Wilson and then in the future become a writer herself, "her head would explode".
This year was also Rhys Thomas' first time at Hay Festival.He had a "full circle" moment watching poet John Cooper Clarke take to the stage, after first seeing him while working at his local festival aged 16.
"I just didn't realise that poetry and literature could have that raw edge to it," he said."He was funny, he was swearing. He's a rock and roll star who uses poems instead of guitar solos."