Hi Wayne,
I have not fished Collingham in the few years I have been on the tidal. 15 anglers around me fishing on the Trent is my definition of hell - actually, hell might be a more favourable place. Sometimes, August can be a strange time & good on you for trying so hard to try & swing things in your favour. Autumn coming round very soon & all fish around will be getting their heads down.
Do try & get away from the crowds, I cannot stress that enough. Definitely in need of a downpour, for me I reckon that three weeks of rain would be a good start to saturate the ground. My construction friends do not share my considerations mind...
Try posting these kind of reports in the Tidal Trent Section. Sometimes, contributing on a river thread, no specifics, conditions, flows, colour, bits of interest, people might open up a bit; but very rarely would this be seen for all to see.
Hope this helps,
Cheers, Jon