The big flaw unveiled in the thorough post-election inquiry for the industry, by Prof Patrick Sturgis, has not been satisfactorily addressed.
The root problem, he found, was not last-minute jitters in the ballot box or inadequate turnout filters, but rather a brute failure by the pollsters to interview the right people.
A couple of door-to-door surveys run by academics and published long after the event did get election 2015 right. The big difference was that these surveys picked out voters’ names at random, and then kept hammering on their doors until they answered.
The other polls, whether online or phone, give up on the hard-to-reach, move on to other phone numbers and email addresses, and thus fail to achieve a genuine mix. In 2015 it transpired that Tories, for whatever reason, were that bit harder to rouse, creating the big polling miss.