Hi, I had heard that if you need your passport frequently for business travel, that you could apply for a second one, so I did a Google and found this here -
http://www.businesstraveller.com/discussion/topic/getting-a-second-uk-passport
I hope it's useful. I don't think there is any way of getting your visa without surrendering your passport.
I was going to say that if they dropped off their paperwork in person and collected in person then there would be a fair chance that all would be processed in 4 days - and then I remembered that I don't think you can collect from Manchester, it gets posted back to you. Going in person to Birmingham might get it done in time.