Catch21, normal operations are with one TFO/observer in the front and one in the back. The one in the front has visibility of the CAD and Warning panel, also hears the audio warnings. The rear seat observer has no direct visibility of the displays in the front and in most aircraft no audio warnings from the aircraft, therefore would rely on the front seat occupants relaying what was going on.
I would have expected a conversation to have taken place during the return towards base between the 3 crew along the lines of...Pilot (insert name) do we have time/fuel to fit in task xxxx over the city? Quite a lot of non urgent tasks are received and stored, then when the aircraft is called out on an urgent task the crew will try to fit in the 'stored tasks' that are near the route/base. It reduces transit time and cost to individual non-urgent tasks. Some non-urgent stored tasks become increasingly urgent if they have a carry out by a certain date/time request. The start of shift briefing would include a briefing from the police TFO to the pilot of what stored tasks really needed to be completed during that shift (many can only be achieved under cover of darkness....equally, stored photographic tasks are done by day.