All good comments here folks, gonna check those places out.
I bought a fairly comfy pair of jeans from sports direct ( I know I know ) "firetrap" branded but the fit is awful, they slide down without a belt and with a belt still look ridiculously baggy, size down is too small...
Obviously I don't expect you to drop everything and rush over there, but I've found for years, that if I'm in the U.S., I can go to any Mall with big department type stores like Selfridge and John Lewis here, and buy good fitting jeans/chinos off the peg.
They may need adjustment in the leg, I'm barely 5'9", but they fit good at the waist and hips, mainly because a lot of U.S. stores carry odd sizes, like 31", 33", 35" waist, so if your waist is 34", but some jeans/chinos etc. feel a bit snug, you can buy 35" in the U.S., where you'd have to get 36" in the U.K., then have them taken in.
Stores to look for, almost always in Malls, are Dillards, Macy's, Nordstrom, even Neiman-Marcus, who have a rep for being expensive due to the fact that oil men's wives flock to their Dallas TX locations.
If you ever go over, try those stores and see.