Hi all, I forgot to post last week, but we've had several updates:
On Wednesday the 17th I sent an email to my local MP, and they contacted the Home Office. The Home Office then informed my MP that they had made a decision, and would be sending us the official confirmation email within the next couple of days (a rather suspicious coincidence...). On Monday the 22nd we received the official email, 49 working days after our application arrived in Sheffield, and began the agonising wait for the tracked package, which arrived on the 24th with... an approved visa! Thank God. My wife arrived in the country yesterday, and we're delighted to (finally) be reunited.
Thank you enormously all those on this forum who have been so very helpful, it's really been a wonderful support (and I'm sure I'll be back posting here in a couple of years for the next stage). I wish all those still waiting through this horrible process all the best, and hope that you receive positive decisions soon.