London-based fact-checking site Full Fact has had its work cut out in the past couple of months: The intense campaign building up to Thursday's referendum on the United Kingdom's membership of the EU referendum has been littered with questionable facts.

With a recent survey showing knowledge of basic facts on the EU still imperfect, fact-checking seems as necessary as ever. Full Fact has fact-checked leaflets, debates and everything in between. In the final days of the campaign it produced concise videos like these on some of the main claims of the two sides:

I reached out to Phoebe Arnold and Will Moy, respectively senior communications officer and director of Full Fact, to gauge their reactions to this campaign.

The EU has been a contentious issue for a while in the UK, with the debates between Nigel Farage of UK Independence Party and former Liberal Democrats leader Nick Clegg building up to this referendum. Were you mostly ready for the topics that ended up dominating the campaign or did something surprise you?

The Farage/Clegg debates during the 2014 European Parliamentary elections helped prepare the ground. We have covered the same topics, albeit in more detail and with more up to date research — for example the UK's EU membership fee, how many laws are made in Brussels, how many jobs rely on our membership, and immigration.

We've been preparing for this referendum for at least two years. We've built up a network of supportive academics who've been able to help at short notice on the thornier topics like the Transatlantic Trade and Investment Partnership's effect on the National Health Service or what happens to UK expats in the EU and EU citizens in the UK if we vote to leave.

Closer to the referendum, we have been guided by Ipsos Mori's issues that will decide the referendum. And, lo and behold, we've had more traffic on the topics that people care about: the economy and immigration.

What has been your most popular fact check on the EU to date?

Our fact check on the UK's EU membership fee has had three times the traffic of all other articles. One tenth of all our pageviews went on this piece.

On what EU topic do you think you've had greatest impact?

One of Vote Leave's headline claims is that we send £350 million to the EU every week — this is not true. Unfortunately half of the public still believes the claim, according to a poll Ipsos Mori did recently [Editor's note: linked in the introduction], despite our efforts to debunk it and those of the official UK Statistics Authority.

On the other side, we've been fact-checking the claim that 3 million jobs depend on our membership of the EU since 2011. Having that sort of runup time seems to make some difference.

The Remain camp have been making the claim in a more justifiable form since we fact-checked the EU debates in 2014: 3 million UK jobs are linked to trade with EU countries. Whether the public takes this to mean those jobs depend on membership is another question.

How did the campaigns react to your work?

We've been quoted by senior figures from both sides including Suzanne Evans, Business for Britain and Sarah Wollaston minister of parliament.

We haven't been asking for corrections during the referendum as we normally do. This is partly because that relies on building constructive relationships with the people you're trying to persuade — and this is a highly polarized debate led by temporary campaigns. In this context, even respected independent authorities like the Statistics Authority and the Institute for Fiscal Studies have been told they are wrong when they have tried to intervene on factual issues.

Do you think people will vote on the basis of facts?

There’s no set of facts that can make your mind up about this issue. We hope that having the facts helps people ask important questions of campaigns, and to choose what to focus on when making their decision. Ultimately, it’s up to voters what they care about and what they base their decision on.

Lots has been written about the role of facts during this referendum. Do you see any parallels with the Trump-induced "crisis of fact-checking" in U.S.?

This is something we will be thinking more about.

On the one hand, there are lots of reasons to be optimistic about the UK political scene. Our work has never been so widely used or widely supported as during this referendum, and academic experts have been rising to the challenge of informing the public with gusto.

On the other hand, there are signs of people willing to make bold claims with no basis in fact, and to stick to them when challenged.

It is too soon to say there’s a general international phenomenon here, but it’s not too soon to be cautious and try to make sure we are learning from our colleagues in the USA.

Did you make any interesting mistakes?

We’re always happy to correct and clarify articles. In this referendum we've definitely added depth and more angles to various pieces (e.g. laws made in the EU, another popular topic). But our work now goes through a structured three stage review process and is often reviewed by external academics.

Unfortunately, we did need to correct an older piece on the membership fee that dated back to 2014. We (and others) had misunderstood the way the rebate on UK’s membership fee for the EU is paid — or rather not paid, as the discount is applied before any money leaves the UK. That makes a difference to what figure you give as the highest possible amount we pay as our membership fee.

In March I (somewhat facetiously) asked whether facts would be victims of victors in this campaign. 99 days later, are you ready to answer that question?

We’re concerned that both campaigns have damaged trust enough that even when they’re right in what they’re saying, many people won’t listen (and actually that may be justified by experience).

If that’s true, both politicians and the public lost out.