PANEL 1: The shots of Hartnell used here are from The Space Museum. There were two challenges with adding Hartnell, the first being to find shots where he’s either looking the right way or where he’s got the right sort of gesture or expression you need for each frame he’s in.
PANEL 3: The shot of Hartnell used here is from The Time Meddler, IIRC. Having Hartnell in the Tardis talking to the Time Lords with Pat had a chat with the Brig made things a lot easier. It also helps make things different enough from the TV Original to be worth the effort of compositing all these frames.
PANEL 5: Colourising Hartnell was relatively straightforward. Given that I’m not Stuart Humphryes I was always going to aim for a more simplistic style. Since the conceit is that the images here have been “painted” instead of being screen grabbed, an artwork filter was always going to be applied to the original composite. But Hartnell was colourised using just three tones for the skin and three for the hair. By the time the filter was applied, they merged nicely to help with the illusion.