Walkers has officially removed the milk powder from Thai Sweet Chilli Sensations, meaning they are suitable for vegans
Be advised that some with milk powder are apparently still on store shelves, but these will eventually circulate through and be replaced with vegan ones.
Walkers and Lay's have substantial overlap both being owned by Frito-Lay, but I've seen no indication so far that the Thai sweet chilli Lay's chips are getting this same treatment. So I didn't want to potentially mislead anyone.