Not being British I do not know what chip butties are. Can anyone tell me what they are?
As near as I can tell, it's French fries on a hamburger bun, maybe with mayo?
Not British either, but have had these in Canada, U.S. and U.K. As an adult, heavy drinking was involved. Chips (potato fries) served on a soft bun. The bread is buttered, the chips are greasy and salty. Ketchup, HP sauce or malt vinegar was offered to top them off. No mayo was involved. As a young child our family always went out for or took out fish and chips every Friday. Most of them served soft floury buns called baps to make your own butties with the leftover chips.
I don't think my system could handle them these days. That said, not that long ago I had a sandwich made with pulled barbeque pork,
cole slaw and chips on it. (Food truck.) It was memorable!
Bacon butties with HP used to be our go to hangover cure.