The full analysis is here. The summary is that our estimates weren't too bad on average: the distribution of errors is centered on zero (i.e., not biased) with a small standard error. But, on-average estimates are not sufficient for the types of prediction we would like to make. At a ward-level, we find that we generally overestimated support for Tory, especially in areas where Ford received significant votes.
We understood that our simple agent-based approach wouldn't be enough. Now we're particularly motivated to gather up much more data to enrich our agents' behaviour and make better predictions.