The Man who thought he was the Doctor.
Jackson Lake comes from 19th Century Earth and was a Maths teacher. He moved to London with his wife Caroline and his son Fredrick. He didn't know that he found some Cybermen and he used an info-stamp to kill some. The info-stamp backfired and made him become the Doctor. He forgot everything that happened that day.
When the real Doctor arrived in London Christmas Eve he heard a woman calling the Doctor who he thought was him. She said you aren't the Doctor then appeared Jackson. When the doors of a shed opened a weird metal creature was their a Cybershade. The Doctor and Jackson took out a Sonic Screwdriver each but Jaskson's was an actual Screwdriver. Cybershades are fierce creatures who act like cats and dogs. Jackson says he was hunting them down for months now. He put some rope over the Cybershade but forgot to let go when it was climbing up the wall. Also the Doctor did the same and they slid through the floor of an abandoned building. Rosita managed to break the rope free so that when the Cybershade went through the window they wouldn't.
Jackson indeed made a new friend but the Doctor tried to jog his memory by saying remember the Weeping Angels you know the blink. Jackson thought he was a strange man but anyway he ran off to investigate a murder of a reverend. When Jackson entered the house he saw the Doctor and explained why he named his scredriver and Sonic one. Anyway they investigated the house finding lots of Info-Stamps which showed them information. Then 2 Cybermen appeared out of nowhere and chased them up the stairs. Until when the Doctor was holding them back Jackson used an Info-Stamp and killed the 2 Cybermen. He tried to remember where he had seen it before. When he took the Doctor back to his base he told him the first murder was of a man called Jackson Lake. The Doctor later looked at his watch with the letters JL on it. Then Jackson knew he wasn't the Doctor and remembered they killed his wife.
Before some of this happened Jackson showed the Doctor his Tardis which infact was a hot air balloon. When the Doctor and Rosita went to investigate Jackson stayed at base. Some charity men were taking the kids to the Underground and they were to be used as a work force.
The Doctor and Rosita were trapped by Miss Hartigan and her Cybermen so Jackson appeared from nowhere and again used the Info-Stamps to kill the Cybermen. The crew ran off to free all the children. When they got there the Doctor knew that the place where to children were was about to blow so him and Jackson used the Info-Stamps to kill the workforces Cybermen.
Jackson remembered what the Cybermen took it was his son but his son was about to die by standing on a platform which was going to fall. The Doctor saved him and the children and ran back to Jackson's headquarters. Later on Jackson saw his Tardis flying proudly up in the sky facing off against the Cyberking. Him and lots of the Londoners saw a blue light come from the Tardis it was the Doctor killing the Cyberking and instead of it falling and killing lots of people he sent it through the Time Vortex.
In the end Jackson made everybody cheer for the Doctor and was talking to him when he was about to go into the real Tardis. The Doctor showed Jackson the inside of the Tardis and Jackson was happy and ran back out with a smile on his face. Just before the Doctor was about to go Jackson invited him for Christmas Dinner. He knew the Doctor didn't do Christmas Dinner but anyway the Doctor said that Jackson was one of few who actually persuaded him to have some. So both of them went and had some good old Christmas Dinner.
He has appeared in:
The 2008 Christmas Special: The Next Doctor