TIMELINE for In-country Tier 2 Priority General Visa Application:
26 October 2016, about 1:30pm: Requested priority service, not successful
27 October 2016, about 9:30am: Requested priority service, SUCCESS!
27 October 2016: Completed online application for priority, paid for immigration health surcharge, and posted supporting documents through priority mail
28 October 2016: Documents arrived at the UKVI in Sheffield
31 October 2016: Email acknowledgment of my online application and my mailed documents
1 November 2016: Received biometrics letter (post marked 31 October)
1 November 2016: Completed biometrics at Post Office near me
8 November 2016: Visa approved. I got no email, just a letter by post saying it has been approved and it came with my passport
I am just waiting on my Biometrics Residence Permit to be sent, but all in all this process has been completed!
It was 500 extra pounds, but very very very straightforward and took 14 days from start to finish. Very happy!