Four days out from my Big 10k on Sunday... I'm going to predict a time of 51:49 for myself. To put that in context, my fastest ever 10k is currently 51:11 but that was on a very flat course. Sunday's run has two rather significant hills and my only other 10k race was on quite a hilly course, back in June, and I did that in 53:26.
And good luck to ancientrunner for the GNR.