Appointment was at 8am, got there at 7:15, there were more than 20 people in front me waiting at the doors. In addition there were other people not queuing but standing about chatting - they turned out to be immigration agents. They were let in first when the doors were opened at 7:30.
After clearing security they we had to queue to get our application checked over. This process takes about 10 minutes. I nearly got tripped up here since when she asked to see proof that I worked for such and such a company (as stated on my Work Permit), I didn't have it since I actually worked for a subsidiary. I'd forgotten to tell HR to point that out on the employer letter. Fortunately about a minute later she said it was ok since she'd managed to find on her computer the relationship - which she wrote down on a bit of paper. She also asked for the Life in the UK pass notification letter and a payslip. She checked the photographs too. Presumably if there is a major problem with your application they actually prevent you from paying and wasting a lot of money - which is something you don't get with the postal applications.
After she stamped valid on my application I was given a number and sent upstairs to pay. Some of the immigration agents were there paying too and they all seem to be paying in cash which was interesting. I wondered if I should have bought cash too - I was suddenly worried there would be a problem with my debit card, but the payment went through ok. There was a sign up saying they wouldn't accept cash any more from early August.
By 8:15 I had finished paying and had to wait for my number to be called. There was virtually nobody there so I wandered over to where all the immigration agents were and told them I had an 8am appointment but they just laughed and said they don't actually start the interviews until 9am. Between 8am and 9am they only accept applications from the immigration agents. There was quite a bunch of them coming and going all dropping off about 5 applications each at a special window just for them and then walking off after being there for no more than 10 seconds.
My number was called first at exactly 9am. I went up to the window for the interview which was quicker than the application check downstairs.
First he wanted the application and the handwritten page that the lady downstairs had written with details of my Work Permit. Then he started going over my application.
I had been out of the UK 54 times for a total of 235 days absent (not counting the day I left and day returned). I was worried about this more than anything, but he didn't flinch when he saw it and starting scanning the date left and the date returned rapidly - presumably looking for long absences. After less than a minute he finished going through the absences and started asking for documentation:
* Life in the UK Test Result
* Last three payslips (I gave him 4)
* P60s (gave him 5)
* Last three bank statements
* Employer letter (which they kept)
He spent a few seconds looking at each one then said he now had all the necessary documents assess the application. He said it would take about 1 and a half hours for that to be done and the stamp to be put in the passport. He said I could leave the building then to come back at 10:30 and wait for my number to be called.
So being a nice sunny day I went for a coffee outside in the nearby shopping pedestrian mall.
I came back at 10:15 allowing time for the security queue, but they waved me past the queue straight to the security scanners and I was back on the first floor in only 2 or 3 minutes. At 10:30 exactly they called my number and I found out the good news!
Other notes:
* They didn't ask to see my work permit, HSMP Letter, or Tier 1 letter. In fact when they looked in my passport they seemed to be only interested in looking at my work permit - which had been cancelled many years ago but waSs originally valid for 60 months. (In theory I didn't need the HSMP or Tier 1 since I ended up sticking with my original employer the whole time).
* The letter they issued me doesn't mention ILR at all - it just says "I am returning the enclosed passport endorsed with an extension of stay in the United Kingdom." There was also an informational leaflet that specifically said "THESE NOTES ARE FOR INFORMATION PURPOSES ONLY AND DO NOT CONVEY THE GRANT OF ILR."
* I had a huge amount of other documentation with me like 5 years of bank statements from two different banks, utility bills, 5 years' worth of pay slips and all kinds of other documents. So much so my bag handle actually broke during the course of the day it was so heavy. None of it was needed.