My wife has heard that people in London don’t wear jeans and sneakers. Not wanting to stand out like a sore thumb, she has asked me to post this thread and ask UK-Dopers what she should wear for her March (12th-20th) trip.
She plans on doing the usual touristy stuff: Palace tours, Tower of London, Greenwich observatory, Hyde Park, British Museum. They also plan on having tea at the Orangery (if they have it on Sundays).
Thanks!
Jeans are ok, but she’s right about sneakers (called trainers here). And the Orangery is indeed open for afternoon tea on Sundays.
Why change shoes or clothes you like just to fit in? If you go to the tourist spots I think they already know you are a tourist.
is incongruous with this
Saturdays are nudist day at all the Art Galleries.
That’s kind of my thinking. However, I’m not going. 
Surely, you jest!
People wear a wide range of costume in London, and a person wearing jeans and sneakers will not be noticed at most of the usual tourist places. You’d only raise eyebrows at somewhere like a really upmarket restaurant.
Just say “screw it” and wear a cowboy hat.
Somehow I imagine that actually starting some interesting conversations with friendly locals.
I say screw it. Go all out. Tell your wife to wear sneakers, brightly colored sweat pants, a sweat shirt with a large air brush design of an eagle on the front and a religious slogan on the back such as “Jesus is my copilot” on the back. A baseball hat or sponge rollers make good head entire. When someone mentions something about being an American, she can act offended and claim she is Canadian.
Fanny pack. And CALL it a FANNY pack!
I always wear jeans and trainers and I have never encountered any difficulties with that in London or anywhere else in Britain. On several occasions I have been asked for the way somewhere by natives, so I don’t think I stand out as a non Brit.
Some reading for your wife so she won’t feel so confused when in London: link 1, link 2.
I haven’t heard it’s sneakers/trainers in general but specifically running shoes which are predominantly white, like these, that are seen as “very American” when worn as everyday shoes.
They’re frowned upon unless paired with a bright Hawaiian shirt, in which case they become the height of fashion.
From Denver, though I’ve been sorta-kinda quasi-living in London for the past few months. I’ve worn sneakers and jeans every single day and haven’t had a second thought about it. It’s probably worth noting that I’m historically oblivious to fashion trends and usually far too deep inside my head to notice the attire of most people around me (certain female company excluded) so I guess I’m not the best person to give advice here.
Ironically, the only time I felt uncomfortably out of place was at an American-dominated bar gathering for the Super Bowl. Go figger.
When I was in Oxford as a high school student we thought we were blending in pretty well - it seemed like all the British teenagers were wearing the same jeans and Doc Martens as we were. We passed a street musician who yelled, “Hello, Americans!”
We asked him how he knew we were Americans, since we hadn’t been talking, and he said, “You walk like John Wayne!”
Yes, particularly when worn with ‘Mom’ jeans, a windbreaker and a baseball cap.
If her jeans are perhaps more boot cut or ‘skinny’ and the trainers more like something from Onitsuka Tiger (slimmer construction) - hey, why not. But not to high tea - different dress code.
She’ll look like a chav. Or a failed chav if she’s older. I suggest she wear some sensible shoes. And jeans probably aren’t the best choice either. Not because of looks but because of water absorbency. It tends to rain or snow or both in March! Slacks or a skirt will dry out much more quickly than jeans.
Jeans and trainers are perfectly common. Nobody will raise an eyebrow - or even notice. You might not get into many nightclubs like that, though.
As with everything, it depends on where you’re going and what you’re doing. As people have noted, jeans and trainers aren’t going to get you into the nicer places, but I doubt that’s much different over there. Plan for rain and cold weather, even if it doesn’t look like it’ll rain, and after all that, just go for comfort. I doubt we’ll mind all that much on our end!