I don't think he's called Grant Gordon in the entire episode. Page should therefore be Grant (The Return of Doctor Mysterio). Can we check the comics?
Talk about it here.
Grant Gordon was a man who gained "superpowers" and went under the alias of the Ghost. Grant gained his powers by accident as a child, due to mistaking the Hazandra for medicine.
For 20 years he kept the promise to not use his powers, until the Doctor could return.
Eight years after defeating Harmony Shoal, the Doctor returned and took Grant and his family on as companions in an adventure to find the sisters to the crystal inside Grant.
Biography
Meeting the Doctor
Grant met the Twelfth Doctor as a child, when the Time Lord accidentally fell into his own trap to prevent temporal paradoxes in New York. Initially mistaking him for Santa Claus, Grant was corrected; due to his love of comic books, he dubbed the stranger "Doctor Mysterio". He was given the Hazandra, a small gem, and led to the roof, where the Doctor explained he was trying to straighten out the paradoxes he caused. When the Doctor asked for the gem to power his device, Grant revealed that he ate it, having mistook it for medicine for his cold; at that moment, the Doctor revealed that it granted wishes and Grant got his superpowers. The Doctor made him promise not to use his powers until he returned.
Teenage years
In his high school days, he fell in love with Lucy Fletcher, but was not able to confess his feelings for her. Puberty caused frequent instabilities, including one occasion where he was unable to turn off his X-ray vision and saw naked people everywhere. He would also levitate without meaning to do so. During this period, the Doctor kept an eye on him.
Becoming "the Ghost"
Years later, Grant broke his promise by taking on the superhero identity of the Ghost, this led him into a confrontation with Harmony Shoal, which planned to takeover the world by replacing the brains of world leaders with aliens. During this adventure, Grant reunited with the Doctor and revealed his true identity to Lucy, who had become a reporter covering his exploits as the Ghost. (TV: The Return of Doctor Mysterio)
Grant and Lucy got married. (COMIC: Ghost Stories)
However, Grant didn't stay away from being "the Ghost" for long. As his step-daughter grew up, "bank robberies and all that flying off midsentence" were "commonplace". (COMIC: Ghost Stories)
Travels with the Doctor
On the 26 December eight years after the Harmony Shoal incident, Grant re-encountered the Doctor while stopping a robbery at the City National Bank. The Doctor wanted Grant's help in finding the other three crystals like the one inside Grant. Grant refused to go with the Doctor unless he could bring his family, so Lucy and Jennifer came along on the quest. (COMIC: Ghost Stories)
Superpowers
Ingestion of the Hazandra, combined with his love of comic books, gave Grant numerous superpowers. He was capable of flight and levitation, able to travel through the air at high speeds, including the vacuum of space. He also had superhuman strength, and was able to stop the Shoal spaceship from crashing into New York City with just his non-dominant right hand. Grant possessed super-hearing which the Doctor utilised to communicate to him via frequencies no other person on Earth could hear. X-ray vision allowed Grant to see through solid objects, including clothing. He was also pyrokinetic, able to light a candle with a snap of his fingers. (TV: The Return of Doctor Mysterio)