At the San Telmo museum in the Basque city of San Sebastian, in northern Spain, there is a picture of a group of children from Guernica, the town flattened by the Luftwaffe in 1937 as an experiment in the blitzkrieg technique later used on British cities.

A caption explains that these young survivors were among 4,000 refugees taken in by Britain after a reluctant UK government bowed to public pressure.

They were placed in small "colonies" across the country, from the Isle of Wight to Carlisle, while war raged between General Franco's Nazi-backed fascists and the republican government.

The parallels with the current situation in Syria are clear. At the beginning of September, David Cameron was forced to acknowledge a growing public empathy for refugees caught between Assad's government and Islamic State, and announced that 20,000 would be admitted under the Syrian Vulnerable Person's Programme over the next five years.

Empathy is hard won, and it took an atrocity of the scale of Guernica and later Kristallnacht to persuade people of the full horror of fascism in the 1930s.

It was pictures of three-year-old Aylan Kurdi, drowned on a Turkish beach, that helped to turn UK public and political opinion in favour of granting refuge to those fleeing the situation in Syria.

But even now, as Mr Cameron has made clear, those refugees will only be accepted on to the scheme from camps in the region, not if they have made their own way to Britain via the Mediterranean. Those who qualify will not be granted automatic asylum. Instead, they will have a special humanitarian status with the right to apply for full asylum after five years.

Part of our image of ourselves as a nation is that we are welcoming of refugees. But the reality is more mixed. The welcome we have given has always been limited and conditional, especially on an official level. Even when ministers finally agreed to let the Basque children in, the government refused to bear the costs of the scheme, which was left to campaigners.

It was always understood that the children's stay would be temporary and the majority returned before the outbreak of the Second World War, when Franco took full control of Spain in 1939.

The system developed for the Basque children was later applied to the Kindertransport, where private citizens were expected to cover the costs of Jewish children fleeing Nazi Germany.

The politics of asylum has always been intertwined with wider issues of immigration and social cohesion. Secret papers released in 2009 revealed that Margaret Thatcher had warned her cabinet in 1979 of "riots on the streets" if a UN quota of 10,000 Vietnamese boat people were given council houses in Britain.

More recently, refugee crises have fuelled shifts in UK foreign policy in a profound way. The apparent powerlessness of the international community to act in Rwanda and Bosnia led Tony Blair, among others, to throw their support behind the concept of humanitarian intervention, tested first in Kosovo in 1999.

The Bosnian conflict also had its effect on domestic asylum policy. One of the most successful schemes to settle refugees in this country was set up for Bosnians in 1993 by the Refugee Council and the Red Cross, who helped settle 1,000 men and their families in reception centres around the country.

Empathy can soon turn to fear in the face of the international terrorist threat. When it emerged that a Syrian passport in the name of Ahmad Almohammad was found next to a suicide bomber at the Stade de France, the narrative of the attacks on Paris began to shift. Could it be that the refugee crisis in Syria had been used by the terrorists to infiltrate Europe with jihadis? We still do not know the answer.

Although the self-appointed Islamic State has claimed responsibility for the attacks, the perpetrators appear to have been mainly French and Belgian nationals, home-grown recruits to the totalitarian Islamist ideology.

And yet, the British government was forced to issue a statement over the weekend assuring people about the stringent checks being made on Syrians entering this country. Theresa May said refugees would be vetted twice: once by the UN High Commission for Refugees in the camps on the Middle East and a second time by the UK Home Office when they enter Britain.

This is not the first time Paris has been the victim of terrorist attacks. In January, the Charlie Hebdo killings demonstrated that the French interpretation of freedom of speech is particularly distasteful to those of a murderous Islamist sensibility.

But the French capital was also under Islamist attack 20 years ago when a wave of bombings attributed to the Algerian Islamic Armed Group (GIA) brought mass murder to the streets of Paris.

Throughout 1995, Parisians lived in fear, while anyone judged to look vaguely Muslim or North African were liable to random identity checks at Metro stations across the capital.

The consequences of the attacks on France 20 years ago are still being felt here in the UK. Many of those suspected of involvement found refuge in Britain, including the prime suspect of the Paris bombings, Rachid Ramda.

The French authorities were astonished that Britain was prepared to welcome Algerian Islamist figures as dissidents, when they saw them as plain and simple terrorists. London had already become a hub for the Islamist opposition diaspora and the French intelligence services coined the phrase "Londonistan" for the phenomenon.

A string of extremists from around the world was tolerated by the authorities in the mistaken belief that it made Britain safe from attack.

Political Islamists were genuinely under threat from the oppressive regimes from which they came, but a number of them used their status as refugees to preach jihad to British youth. Omar Bakri Mohammed from Lebanon, Abu Hamza from Egypt and Abu Qatada from Jordan became recruiting sergeants for the international war against the West.

Britain takes great pride in its history of giving shelter to those fleeing persecution. But no one imagined that the international asylum system, established after World War II in a direct response to the Holocaust, would one day be used to give safe harbour to those who shared the totalitarian, antisemitic values of the Nazis.

But then nor had anyone thought there could be such a thing as a right-wing extremist dissident or a fascist refugee.

There have already been the inevitable calls to crack down on asylum seekers from the Middle East in response to the Paris attacks and the government will come under pressure to reassess the Syrian Vulnerable Person's Programme in light of events.

But the 1951 Convention on Refugees is a celebration of shared enlightenment values and it would be a tragedy multiplied if our empathy for the suffering of the Syrian people also lay dead on the floor of the Bataclan.