Jeremy exposed the scandal of his daughter's treatment on Sky News almost a year ago.
A shocking video of Jeremy holding Beth's hand through a hatch in a door prompted an inquiry into the teenager's care and led the health secretary to promise she would be released by Christmas.
Beth now lives in an open plan unit with bespoke care designed to respond to her sensory needs. It means she is free to explore the outdoors, reconnect with nature and enjoy new hobbies like fishing.
Jeremy told me his daughter has a "new found love of gardening and growing things".
He added: "She's hugely into fishing, which luckily is one of my passions." He had thought that was "about spending quality time with me".
But he explained: "It's not. It's about the sensory side of it. She loves the feel of fish and the noise they make when they go back in the water is just amazing.
"Beth is finding out about herself. Every time I see her, Beth's hair is a different colour, a different length, a different style. She's able to go out and buy clothes."
In just 12 months, Beth's life has been completely transformed. Jeremy says that is because autistic people have been involved in planning her care.
"The difference now is Beth is surrounded by people who fully understand autism and her part of the spectrum," he said.
There had been "pathological demand avoidance" and anxiety, he said. These were triggering "challenging behaviour that services were struggling to cope with".
Strategies to remove the anxiety also remove the triggers and "remove the behaviour", Jeremy said.
He explained: "It's as simple as that. The right people in the right place, the right environment, supporting her in the right way."
Beth is 19, and spent four years locked away - important teenage years that are lost forever.
Jeremy said he does not want the same to happen to other autistic young adults who are still trapped in the system.
He is using his experience to help other families.
He said: "I speak to dozens of parents who are approaching the situation that Beth found herself in.
"I also work as what they call an expert by experience in care treatment. I work with panels that go in to review the care of people in inpatient units and also review people who are at risk of entering the inpatient system.
"So I am very aware of just how many people this impacts."
Beth does not feel ready to take part in interviews herself but responded via her father.
"Beth gave me a message to pass on and it chokes me every time I think about it," Jeremy said.
"And that message is that this has happened because people moved into my world. They stopped trying to drag me into theirs."
Hundreds of young autistic adults remain trapped in the system.
But Beth's story proves there is another way and they too can be helped to live rich, rewarding lives just like hers.