Most Americans could spend a full week in Britain without realizing they’ve actually offended basically everyone around them.
The invisible line

You probably don’t recognize it. British queues are sometimes hard to spot, and it means many Americans don’t realize they’ve cut the line. They might look like they’re standing around. But British people know exactly who was there first, and when.
An American walks straight to the counter. They assume there’s no line, but really, there was, and British people take queuing pretty seriously. You wouldn’t really understand it unless you lived there.
The missing word

It’s perfectly polite to say, ‘Can I get a coffee?’ in America. But not in the UK. People over there take it like a command, and they think it’s rude not to use ‘please.’ They use it constantly. ‘Please’ comes when they’re ordering food, when they’re asking for directions, everything.
Brits are used to it. For Americans, tone of voice is more important, but Brits listen for the actual words. Missing ‘please’ makes you sound kind of abrupt.
The café line

Another thing we’ll do is say something like, ‘I’ll have a coffee.’ Totally normal here. However, for Brits, you’re supposed to make it into a question, like ‘Could I have…?’ The more words you use, the politer you are.
British people think it’s rude to be so direct when you’re talking, and especially in smaller cafés. It’s more personal there. We might be more friendly overall, but Brits think we’re bossy.
The table problem

That’s not all. Americans tend to be more direct in restaurants, and we’ll say an order’s wrong when it is. We’ll straight-up tell the server there’s a mistake. Brits, though, circle around the problem first. They’ll apologize themselves and point out the mistakes very indirectly.
Doesn’t matter that the restaurant messed up. A loud or direct complaint makes British people uncomfortable. They’d rather eat the wrong meal than create a scene over it. How weird is that?
The too-clear invite

There’s something so vague about British invites. They’ll say, ‘You should come by some time,’ and may not actually mean it, but we’re way more straightforward. We’ll directly make plans with someone. It’s kind of rude to Brits.
They think you should be softer around invitations so that the other person has a way out. Making plans openly? That’s not how they do things. They think it’s less friendly and too controlling.
The early knock

You’re respectful for showing up early in America. You’re rude for doing it in England. When dinner’s at 7 in the UK, they’re expecting you to arrive after 7, maybe around 7:15. They don’t want to see you at 6:42.
British hosting culture involves a lot of last-minute preparation. Turning up early ruins that, and that’s why it’s safer to be five minutes late over there. Otherwise, they’ll think you’re being rude.
The bus moment

You’ll notice this if you travel across the pond. People thank the bus driver when they get off. In big cities and small towns, they make sure to show their gratitude to the driver. They’ll give a quick ‘Cheers,’ then step off.
It’s not like missing it will start a fight. However, Brits definitely notice it when Americans don’t do it, and they think it’s disrespectful.
The final bite

One cookie on a plate tells you everything you need to know about British culture. Americans grab it after a minute or two. They all move on. But in Britain, you’re stuck in a weird sort of social limbo, where nobody wants to take it too fast.
People insist on offering it to each other. They all want it. Yet they’re not allowed to be direct about it because it’s more polite to offer it around first. The cookie probably goes stale by the end.
The menu tweak

You’ve got so much freedom with the menu over here. You can get extra sauce and different bread. Hold the tomato? That’s fine. But English people think it’s rude to get so many substitutions. It’s not because you’re inconveniencing them or anything.
They just think that you are. They have an idea that the dish already exists in the way that it’s supposed to, and asking for too many changes makes you difficult. There’s nothing worse than being difficult, apparently.Â
The small sorry

British people apologize way too much. They’ll do it when it’s not their fault and when nothing happened at all. Two strangers could bump into each other. Both of them apologize. The issue here is that Americans aren’t used to apologizing as much as British people.
It makes everyday interactions a little harsher. Brits assume that the other person’s going to say sorry when they reach across or brush past a chair. But they don’t. Now they’re seen as rude.
Sources: Please see here for a complete listing of all sources that were consulted in the preparation of this article.