Arrived pretty early - lots of people in line, but I went directly to a member of staff who literally escorted me to the front and I bypassed the whole line. Through security, around the outside of the building and then to a desk where a number was issued. Into a big holding area with lots and lots of seats (think conference centre/bus garage circa 1970) with a big screen showing numbers as needed to go to a window.
First window was handing over documents and then told to take a seat again, then quickly I was called for the 'interview'. 3 or 4 direct questions, how did we meet, when did we meet, why we chose to live in the US and not the other way round. And that was that. Told I was approved! Quite straight forward, but nerve wracking all the same. Straight to Selfridges for celebratory champagne!