Amid the deluge of updates from pollsters on the state of the race, they are trying to get to the bottom of an increasingly apparent problem with their findings - they can vary quite a lot. The difference isn't just a few percentage points between both sides, as some polls in the last fortnight put Remain is ahead by as much as 18 points, while others put Leave ahead by as much 4 points.

Pollsters have yet to work out why they're getting such different pictures about what Britain thinks on Europe. They are led ultimately by who they survey: if 100 people are polled and they all want Remain, they would have to report it as such. Pollsters try to account for this by asking a range of other questions so they can balance their views as part of a nationally representative sample, but they're still coming back with considerably different impressions of how popular Remain or Leave is with the electorate.

Many think the problem lies in how pollsters get voters' views. Both ICM and ComRes have found that polling voters over the phone turns up a stronger level of support for Remain, while surveys conducted with an online panel find Leave performs much better.