Clad only in pyjamas, and equipped with a dummy and his mum's handbag with his train set tucked safely inside, the brave toddler set off for his nana's house to raise the alarm after mum, Ann, fell into a diabetic coma.
"If he hadn't done what he did, I wouldn't be here now. By the time the paramedics got to me, my blood sugar wasn't registering at all," says 43-year-old Ann, from Bramley, Leeds.
Single mum Ann is an insulin-dependent diabetic who needs to inject herself with the hormone four times a day.
Since she gave birth to Danny she has no warning she is in trouble as the symptoms of low blood sugar or a "hypo" attack - such as headaches, dizziness, blurred vision and pins and needles - have stopped.
So she tests her blood sugar seven times a day, boosting her levels with a sugary drink or snack.
But at night she is helpless and in February 2002, Danny woke up in the early hours to the sounds of his mother in a potentially life-threatening coma.
The little lad tried in vain to revive mum Ann with Lucozade but to no avail.
From the age of two Danny had been taught to dial 999 when his mummy falls down or "acts silly."
But having just moved house, the phone was not connected and so Danny decided to walk to his gran's house a mile away to raise the alarm.
Ann says: "I've always been safety conscious and I'd hidden the door keys on the top of the fridge. Danny dragged a stepladder from the pantry, got the keys, unlocked the front door and locked me in again.
"When I came round I asked 'where's my little boy' and the paramedics told me that he'd gone for help. I said he couldn't possibly have got out of the house. He was only four."
Danny, now six, walked most of the mile to his grandmother's home before being spotted by a taxi driver who called the police. The toddler calmly told them his full address and postcode.
Ann says: "He kept telling them "my mum needs an ambulance, she's in a coma. He only started crying when he thought time was running out.
"Danny is very modest about it all and doesn't know what the fuss is about because he's always been there and cared for me. But I know he's amazing.
Danny's always been my little hero."