Two years ago, Digital Spy featured YouTuber John Smith in our round-up of the best Doctor Who fan videos out there and ended the paragraph with a request that Steven Moffat give him a job, stat.

Now, we’re not saying Moffat reads DS but we’re not not saying that either, because here we are and that very YouTuber is talking to Doctor Who Magazine all about how he was hired by the show to work on some episodes of the latest series, as well as the upcoming Christmas special.

And remember that shot in the first ‘Twice Upon A Time’ trailer that saw footage of First Doctor William Hartnell turn into actor David Bradley, who’s taking over the role for the episode?

Well, it turns out, that was all John Smith.

During the interview, Smith said that he worked on creating the black hole in series 10 episode ‘World Enough and Time’ and added that joining the series has been a “literal dream come true”.

“With the Christmas Special, they’re trusting me with a whole lot more,” John added (via Radio Times).

“All I was given was the original shot of Hartnell and a matching shot of Bradley delivering the same lines. However, there were quite a few differences – delivery, head positions and movement, background – so I knew immediately that a normal morphing transition wouldn’t work.”

He continued to explain how he’d figured out a method that could work after working on a GIF featuring Daniel Radcliffe turning into Elijah Wood, and tried to adapt it to the footage.

“I was familiar with certain techniques where, if you change each facial feature one by one, you can get one person to look like another, with only a few subtle adjustments,” he said.

“So, one facial feature at a time, I gradually turned Bradley into Hartnell, and it wasn’t until I replaced his eyes that it all clicked into place. Even though it looks like Hartnell at the beginning of the shot, it’s still Bradley’s performance and movement, and the ‘modifiers’ are slowly decreased until Bradley looks like himself.

“I still don’t think I’ve quite nailed it, but I’ve got a few weeks before I need to hand in my final work, so I’ve constantly been making tweaks to get it looking as good as possible.”

He concluded: “I’m immensely proud of that shot, mostly since it seemed so impossible at first glance.”