Ashley Stafford was a boy which was invented by Mr Smith.
Ashley loved football and pepperoni pizza. Furthermore he was very good on a skateboard. He was supposed to be Luke Smith who was living together with his parents Heidi and Jay Stafford until he went to the Bubble Shock! factory. He lost his memory and spend the year with Sarah Jane Smith. Then Heidi and Jay asked for their son Ashley on television and showed a photo that looked like Luke. Chrissie Jackson recognised Luke and called the police. Luke returned to the Stafford family.
However, it turned out that Heidi and Jay Stafford were Slitheen who posed as Heidi and Jay. They were working together with Mr Smith who wanted to free the Xylok. He needed Luke Smith for this and created Ashley. (TV: The Lost Boy)