By Lord Ashcroft
The night of 7 May, 2015 is one that most pollsters would rather forget. Different surveys using different methodologies came to the collective conclusion that Britain was set for something close to a dead heat – an expectation that was shattered by the official exit poll and quickly swept away as results began to pile up. My own final national poll, completed the night before the election, also produced a tie between Labour and the Tories. Not only that, I had published polls in more than 160 individual constituencies – some of which proved to be bang on, and others of which, let’s be honest, didn’t.