DW: Would Single market exit 'catastrophe' for Britainthe referendum have had a different outcome had it not been for the refugee policy that Another crisis for MerkelChancellor Angela Merkel initiated Merkel calls for future EU-UK partnershipin Germany in 2015?

Christian Dustmann: I don't think so. Migration certainly played a large part. What was important for British voters, however, was intra-European mobility. That means the free movement of workers within the EU.

The arrival of refugees doesn't play a role in Great Britain anyway. (Prime Minister David) Cameron has already agreed to take in 20,000 Syrians in the next five years. Compared to other European countries, it is an extremely low number. Since Great Britain is an island, it is extremely difficulty for refugees to travel there. In this respect, it was not an issue in the referendum.

In fact, the issue at hand was the fact that there are very few means of regulating migration if the migration takes place within the EU. That was the main argument of the "Leave" campaign.

A survey published in October 2015 speaks for itself: 52 percent of Britons stated that they were most concerned about immigration. Only 14 percent were worried about crime and only 12 percent about wages.

The subject of the referendum in past months was, above all, the British government's lack of control over migration from other EU countries. Once again: It was the most important point. And it often lent itself to extreme and completely implausible scenarios.

Like what?

Scenarios were simulated to show how enormous immigration would be if Turkey were to become an EU member in the future. And, of course, that won't happen in the coming decades. But it reinforced peoples' feeling that they will not have any control over immigration as long as Great Britain is part of the EU.

Cameron's government committed itself to net immigration of 100,000 people per year, once emigrants were tallied, too. The actual figure is around 330,000. It is more than triple the target - but is there really anything to fear when you look at economic factors?

Christian Dustmann is a professor of economics and migration researcher at University College London.

The migrants who come to Great Britain have a better education than the ones who go to Germany. But that did not play a role in the debate. You have to look at the environment to understand the mood.

The economic crisis has hit Great Britain extremely hard. The deficit has risen sharply. It is now at 4 percent. That is the upper edge compared with the rest of the EU. Furthermore, Cameron's Conservative government has been practicing extreme austerity for years. It means that many public services have been cut a great deal - some of them up to 30 percent.

At the same time, the population has grown because of migration and, unlike Germany, a higher birth rate. For example, it has led to the fact the public health sector has become poorer. Waiting times in doctors' offices and hospitals have become longer. Transfer payments have been slashed. Local and long-distance public transport systems have also felt the cuts. Furthermore, actual earnings on the entire income scale have been in great decline for years after the recession. They were - and still are - hard times for people, especially for those who are at the lower part of the income scale. And a particularly high number are in the north of Great Britain.

Before the referendum campaign, Cameron's government partly made the EU responsible for this development. This was strongly supported by the British press, 70 percent of which was for the "Leave" vote. If you have been confronted with this for five or six years - and reports on Europe were not positive before the Great Recession - then a very strong anti-European image is being created.

And it was abundantly exploited by the exit camp. They did not hesitate to lie. Furthermore, it was not convincing to have David Cameron and his finance minister, George Osborne, who had been speaking negatively about the EU for years, now asking people to vote for remaining in the EU.

Since the turn of the millennium, has Great Britain experienced more economic benefit or detriment from immigration?

Economic reality played no role in this referendum. If it had, Great Britain would still be in the union. It was an emotional decision. This has to do with the fact that, in the past seven or eight years, a large portion of the population has seen itself as losing out. And they consider the establishment - whoever that is - as responsible for this. Many voted to leave as a protest against the government.

So emotions conquered reason?

Yes, exactly!

You can try to explain to people that immigration from the EU is something positive for Great Britain. We tried to over the years. But it does not interest people, and it is not what they want to hear. They just ignore it. For example, migrants who have come after 2000 - especially migrants from the EU - have paid far more taxes than they received in state benefits. So it is a gain for British tax authorities.

Is the obsession with Triumph for Trumpcomplete control over the borders a uniquely British craze?

Immigration always triggers strong emotions in people. Furthermore, the debate has been fired up by the tabloids and the UK Independence Party. Last year, 330,000 more individuals entered Great Britain than left it, about half of them from the EU. Cameron's declared net migration goal is 100,000, and he is far from it. That scares people - especially those in the least developed regions, where for years wages have stagnated or even declined. This is then all attributed to immigration, even if there is no evidence that that is actually the case.