He is played by Tommy Knight.
He was an artificial human created by an alien race called the Bane but afterwards he was adopted by Sarah Jane.
In the episode Revenge of the Slitheen, Luke begins attending school with his friend Maria Jackson and later befriends another student at the school named Clyde Langer. Later in the episode, Luke along with Maria, Clyde and Sarah-Jane foil the plan by a family of aliens called the Slitheen, who had attempted to turn off the sun and destroy Earth in order to avenge the deaths of other members of the family who came to Earth previously and were killed by a missile fired at their base at 10 Downing Street by Mickey Smith on the orders of The Doctor.
In the episode The Lost Boy, a couple named Jay and Heidi Stafford claimed that Luke was in fact their missing son Ashley. Luke was given to Jay and Heidi, who proceeded to keep him locked in his bedroom and refused to let him see his friends. One day, Luke tries to escape, only to be caught by his "parents", who reveal themselves to be Slitheen and are in league with Korst, a young Slitheen Luke previously encountered in Revenge of the Slitheen. The three Slitheen attempted to harvest Luke of his telekinetic energy, but he overpowers them and escapes. He later learns that the Slitheen were under the command of Sarah Jane's computer Mr. Smith, who was actually a crystal-like being called a Xylok and wished to crash the Moon into Earth to free his fellow Xylok. Fortunately, Sarah Jane and the Slitheen work together to make Mr. Smith forget his plan and instead make it his mission to safeguard Earth.