Alright, so i finally did a colour change of the old lady. For this i used a linear burn texture over the whole piece set on 54% opacity. I just changed the colour of the pink on her dress from a very intense to a very vague, light pink, which i think works well. I like the drabness of the other two characters, and how they contrast with her cheerful colours. These colours were unsaturated, which i believe still works better than the completely coloured, pictured below.
This is another unsaturated texture, this time with a multiply layer instead of linear burn. I've also basically drawn an enormous white circle from the centre and changed it to linear burn. The difference from the first picture is very subtle, but once you compare them it's an obvious change. It was Simon's idea to do it, as he thought it looked a bit flat and if there was a certain colour change that kind of 'cascaded' out of it, it'd give it new life and depth. I'm pretty happy with this one.