The last update got posted after midnight, so was perhaps a bit misleading. I worked late on the writing.
Today I took the day off work (will work Saturday instead) and got on with some more, quite quickly.
I think I can see my way to the end, although I can also see stuff that will need tweaking (what time of year is this, again, what time of day, etc?) Certainly people's movements around the city will need to be compared to a map, to get it a bit tighter and more accurate.
Overall, it seems to be flowing, although I currently can't see a neat way for the goodies to let the baddies get hold of the 'red herring' documents without getting hurt (mugged) or arousing suspicion as to their real value ('accidentally' leaving them on a park bench).
We should get to the gold, soon.