Sonny Gibson of Ashbourne, Derbyshire, died after suffering terrible burns and inhaling scorching hot air after he became trapped inside the machine.
He was found by his mother Anne-Marie Gibson after she reported him missing when she came back from her friend's house where she had reportedly been sleeping off a hangover. She had originally told police she had been at home with him, but had popped out for cigarettes, and found Sonny missing on her return.
A police officer asked her what her son might have been wearing, and she went to check her tumble dryer. She found Sonny dead inside it, wearing only a pyjama top.
Mrs Gibson, a care assistant, said her son often played hide and seek and hid in odd places. She spoke of her devastation at finding Sonny's body:
'I opened the tumble dryer and he was there. The dryer door was closed. I just opened it and saw him in there, he was just curled up. He looked like he was sleeping, but I knew he was dead.'
Mrs Gibson was initially arrested on suspicion of child neglect, but was later released without charge. A Home Office pathologist said the little boy's body suggested he was lacking in proper social care, and that he was unclean, suffering from head lice and had poor dental health.
He said Sonny appeared to have climbed into the tumble dryer of his own accord, and may have been there 'for anything up to 120 minutes'.
The coroner, Louise Pinder recorded a verdict of accidental death. She said Mrs Gibson's decision to stay at her friend's house rather than return home the night before Sonny's death would 'haunt her for a long time to come'.