I know there's been a few posts on this but I thought I'd post my experience today.
Ended up getting to the station early and got an earlier train than intended. Arrived at the Embassy at 7.20, there were already about 20 people queueing!
I was given a plastic bag for my belt, watch, wallet and coins.
By 07:40 I was through the first checks and security and inside the Embassy. Around 08:00 I was called up to present my documents. Around 08:40 I was called to my "interview". I got asked two questions:
What will I be doing for my employer in the US? I had my answer prepared for that!
Had someone explained my employment rights. Said yes I understood them.
That was it! The interview was less than 2 mins.
I was then told everything was ok.
The longest part was the queue for the courier service, there were probably 10/12 in the queue.
Despite all the warningsI saw 3 people sent away as they had keys/mobile phones/laptops. Also saw 1 guy turned away as he didn't have the paperwork he needed with him.
Also saw a celeb in the queue! Good to see that they get treated the same as everyone else.

cool which celeb?

Richard hammond was there the day i was there

Tony Hadley and what I guess was the rest of the new Spandau Ballet.