Number 4 is wrong. There are some other similar estates. Just a few.

i agree with a lot. the geography is ****** up. the mansion is in west wycombe about 1h15 min northwest of london and 413 mulberry street in nyc doesnt exist. its little things like this that make it realistic or not. especially when they chose such well known places

I think the OP means when the Queen turns up at Daphne's coming out party (in response to the original question I assumed it did not mean she attended them all - but she attended this one because Daphne was the daughter of a prominent politician :-))

You really have context issues.
While cell phones may be ubiquitous now, they weren't in 2003, especially not internationally. Even now, its very expensive.
Lots of people take a tour bus, especially if they have to kill before they check in.
Why wouldn't a small cheap hotel be bustling with people? Or have a juggler who could be planning to busk to earn room and board.
Did they say he lived downtown? There are estates in London. Have you ever been there?
The press were probably invited for political reasons, doesn't mean they were paps.
It's a comedy movie. Don't take it so bloody seriously. You think us films are exact.
The queen was at a dress show, not a coming out. And she always looks bored.
Ian showed up as a worker. Lots of workers get around.
The motorcycle ride was get away scene.
Those who bring sunshine into the lives of others cannot keep it from themselves.