Migration has been the most politically toxic and divisive topic of Jean Claude Juncker's five–year period as President of the European Commission.

And it is from the 12th floor of the Commission building – in the heart of Brussels' EU quarter – where one man has had the role of managing the issue.

Before he packs up his belongings and moves on to new ventures, we wanted to hear from the outgoing EU Migration Commissioner Dimitris Avramopoulos about his time in the role.

I began by asking him to cast his mind back to 2014, around the time of his pre–appointment interview with the European Parliament. He said then that the migration agenda for European policy would be a crucial test of the legitimacy of the European Union. Did he feel that the Commission had risen to that challenge?

Mr Avramopoulos believed that it had:

"We are not where we were five years ago, which proves that we delivered; the flow of migrants has gone down, our borders are better protected.

"We have set up new systems and we have beefed up the existing agencies like Europol and Frontex.

"It is very difficult to convince 28 member states to co–operate in the first place and secondly, to trust each other. This is one of the main problems for the European Union today."

I asked him to explain more about the current status of the border security agency, Frontex. The plan for the 2020 budget is to give over €100 million to the agency, putting more police on the borders. asked him if this suggested a "Fortress Europe" approach and if it wasn't just a direct response to what European governments and their voters had wanted.

Mr Avramopoulos said Europe should never be a fortress:

"I will remind you of something: the very first time this term was used was in the year 1933 by Adolf Hitler. We don't want this kind of Europe, but at the same time, we have to protect our borders.

"Right now we are really in a crucial moment. Jean–Claude Juncker said three years ago that we are crossing important and significant points. It is true. The rise of populism and nationalism is a big threat; they have gained ground."

And did he think that if the migration issue had been dealt with differently by the EU that there might not have been this swing to nationalist parties in various European elections this year?

Mr Avramopoulos cast his mind back over his five years in office for his reply:

"You are in the office where all the main initiatives were taken at the very beginning. We took everything into consideration.

"We wanted to provide support to the frontline member states and at the same time prevent irregular arrivals in central Europe too.

"It was not easy, I have to confess, to put together all the different approaches from national policies, So on the one hand, we had a European policy that we are thinking about and conducting on behalf of all Europeans and on the other hand, we are confronting the hardliners of some countries.

"Here I would like to draw a distinction between member states and governments – and governments should never forget that they come and go."

This answer led our discussion naturally onto the subject of Italy. The country has a brand new government – and a new government means new policies.

I asked him what mistakes the Commission might have made when dealing with the previous Italian government which included League leader Matteo Salvini as interior minister and deputy prime minister. I also asked what he anticipated happening with the new Italian government.

Mr Avramopoulos said the issues were to do with the country's domestic politics:

"I am afraid that a large number of Italians were convinced by all these very easy political slogans. With Salvini in the end, I had started noticing a slight change; he started as an anti-European but began articulating a more friendly political position when it came to Europe. What is happening in Italy is up to the Italian people to judge."

Salvini's position was one of criminalising organisations and individuals helping save the lives of migrants in the Mediterranean Sea. What was Mr Avramopoulos' position on people like ship captain Carola Rackete?

Mr Avramopoulos believes people like Rackete are simply carrying out their duties:

"She was doing these duties based on principles. You must always pay respect to the ones who are doing their job according to principles. And I think that what happened, those are incidents that should never be repeated in the future."

On the subject of those incidents, did he feel that the European response had been on a boat-by-boat, crisis-by-crisis approach rather than informed by an over-arching;policy?

Mr Avramopoulos feared it had – and affirmed that he had repeatedly said that permanent mechanisms are needed:

"I am always pushing on the need for these permanent mechanisms. We can't go on like this in the future. All member states have to understand that now is the moment to adopt a permanent system.

"I want to be frank with you. I was very disappointed with the stance of some governments. Some believe it is a proximity issue, that it has only to do with southern Europe. That is not the case. What we try to do is adopt a strategy for all Europe.

"It is up to the new leadership of the European Commission to articulate a strong pro–European political vocabulary and convince member states. I know it is not easy, but we are not here to do an easy job.

"The future of Europe is at stake if we do not manage to provide permanent solutions on the migration issue."

When Angela Merkel was speaking in the European Parliament last year, the British rightwing Eurosceptic politician Nigel Farage stood up and thanked her for contributing to Brexit due to her Open Door immigration policy in 2015. What were the Migration Commissioner's thoughts on that?

"Nigel Farage's role in Europe – and most importantly in his own country – is a very negative role and this is what historians of the future will judge one day.

"In history, there are two types of politicians and leaders who are remembered:.the ones who were there to build and those who were there to destroy."

One final topic I wanted to touch on with the Commissioner was the European Union/Turkey statement. This was made in March 2016 and was intended to "end irregular migration flows from Turkey to the EU, ensure improved reception conditions for refugees in Turkey and open up organised, safe and legal channels to Europe for Syrian refugees".

Three years later, the EU observed that the "irregular arrivals" were reduced by 97% compared to before the agreement. It also noted that the number of lives lost at sea had "decreased substantially."

Recently, however,Turkish President Recep Tayyip Erdoğan had threatened to disregard the EU/Turkey statement and "open the gates."

What did the Commissioner think the repercussions might be for EU–Turkish relations?

Mr Avramopoulos had an emphatic response:

"The EU/Turkey statement should remain alive. This co–operation should remain and deepen even more in the future. This arrangement should not be used as a negotiating tool."