John was playing with his 18-month-old brother in the front garden of their family home in Bruce Crescent, Hartlepool, when an Asian woman tried to lift Leslie over the fence.
His actions prevented the kidnap and the woman dropped the child and climbed back into an E-registered, burgundy coloured car and sped off with her male accomplice.
The boys' father, also called Leslie, said: "To be honest John is usually a little tearaway. He is always up to mischief. But today he decided to play with his little brother in the front garden and has ended up a hero.
"He heard this woman say `I've got a son now' so he screamed `Put him down that's my brother'.
"He threw a lump of clay and hit the woman on the side of her head near to her eye.
"By this time the baby was screaming, so John got hold of him and ran round to the back garden to tell my wife what had happened.
"I know these people must be sick, but it terrifies me to think what might have happened."Reuse content