I used to be the same way until 1989. I remember it well because it was the first year that me and the future partner went away for a break to Amsterdam. We walked and talked through the streets during the day, soaking in the whole laid back atmosphere. And when we had fish and chips from a corner seller, it was swarmas [there's a food education in itself] and chips with mayonaise on them. Never touched ketchup since unless I've run out of mayonaise. Then I probably go for vinegar anyway. Mayonaise beats ketchup on chips without even trying. Besides, being half-Italian, I can have my cooked tomatoes authentically, as a sauce, any time I fancy. That's proper tomato sauce. Not something out of a bottle or from Dolmio.
Don't like mayo...never have it in sandwiches or on salad. Certainly would never sully chips with it.
There is a place for vinegary old ketchup. But yes, mayo will make an appearance on chips for me too, thanks to my forays into Holland via a Dutch friend.
Holland the region in The Netherlands?.... Tut tut OrangeBoom as my Dutch friend keeps telling me, "Holland isn't a country"
Damn, I'm such an amateur, and that is exactly the type of thing he would of told me. It was Utrecht mostly, for the record!
Walking through the forest at spa with Frittes & Mayo at 7am on a cold damp morning ...NOTHING beats it