You need to find key to Queen Archive and know for sure when Greg Brooks would have his lunch time - then get in and steal 'The Works Master Tape & Outtakes' box - answer is there
There is a digital stereo tape in the archives with rough mixes of (some of?) the tracks from "The Works". That's probably as close as we'll get....unless QP will get off their arses and get demos put together (mix and compilation-wise) for a boxset or special edition CD(s)!