At 17 Niki vowed to give her newborn son, born blind and profoundly disabled, the best life she could. Thirty years on she and Jimmy are travelling Australia in a Toyota Troopy, balancing hard-won freedom with constant care

Outside a supermarket in Exmouth, a small town 1,250km north of Perth, a man notices Niki carrying Jimmy on her back. She is 152cm tall and he weighs 45kg. “He should be carrying you!” the man says.

Strangers often misjudge Niki’s son, who is 30 but looks, she says, “like he’s eight or nine”. Jimmy is blind and has panhypopituitarism, a hormonal disorder that affects fewer than one in 100,000 Australians each year. This condition halted his development, leaving him unable to walk or speak, with severe intellectual disability.

Niki hoists Jimmy on to her back for a walk along the beach in Exmouth. She has always carried him