I know a man who was granted permission to enter the UK on condition that he stayed for no more than 12 months. He was 20 years old, single, and unskilled.
He was, in modern parlance, an asylum-seeker, fleeing from a regime that threatened him and his family - and he did not leave the UK within the allotted 12 months. He became, in other words, an illegal immigrant.
In due course, he was arrested and sent to a prison camp on the Isle of Man. The year was 1940 - and the illegal immigrant was my father, who had left Nazi Germany just four months before the outbreak of the Second World War.
I also know of an 18-year-old woman who arrived in the UK a few months after my father, another refugee from the Nazis, who was allowed in as a domestic servant, but whose mother had to stay behind because, at the age of 41, she was considered too old. The woman who got out was my mother; her mother, my grandmother, who was refused entry, was shot by a Nazi death squad in 1941.
Perhaps these stories help to explain why when I hear the words refugee or asylum-seeker, I think of people desperate to find sanctuary, rather than of unwashed hordes threatening my way of life. And when I'm asked why so many of the migrants in Calais seem to be young and unaccompanied, I think of my parents, both of whom travelled alone to the UK, leaving their own parents behind.
As it happens, both my parents joined the British army and ended up working in a top-secret military intelligence unit, which is where they met. You might say that in their own small way, they contributed to the British war effort. My father spent a total of six years wearing a British army uniform; both he and my mother later became naturalised British citizens and lived unblemished lives thereafter.
I don't regard it as at all improbable that the men, women and children (but mostly men) currently living in such atrocious conditions in Calais will also one day be upright citizens in whichever country they finally are able to settle. Admittedly, they don't look their best in Calais, but nor would you if you'd spent several months, or even years, trekking thousands of miles across Europe.
So why didn't they stop in the first European country they came to? Because Italy and Greece, the main two entry points, simply can't cope with the numbers -- so far this year, according to the latest figures from the UN refugee agency, 98,500 people have landed in Italy and 124,278 in Greece. The biggest groups making it to Italy were from Eritrea and Nigeria, whereas two-thirds of those arriving in Greece were from Syria.
The UN also estimates that at least 2,100 people have been drowned while trying to make the crossing this year, but that doesn't include the 200 who are missing following the latest tragedy off the Libyan coast this week.
Another pressure point is Hungary, where more than 50,000 people have crossed from Serbia so far this year, many of them Syrians who crossed first into Turkey, and then traversed Bulgaria, which has virtually no facilities for handling asylum applications, into Serbia and then to Hungary. (Hungary is now building a fence to try to keep them out.) Contrary to popular belief, only a tiny fraction head for Calais in the hope of finding a way across the Channel to the UK.
Perhaps you think there are no parallels between the experiences of European Jews in the 1930s, and those of the Syrians, Eritreans and Afghans who, as my parents did more than 75 years ago, look to Britain as a safe haven, a place where they might be able to make some sort of life for themselves.
But you may recognise some of the media comment from the 1930s, which bears an uncanny resemblance to the headlines of today. How about this Daily Mail headline from 1938: "German Jews pouring into this country", and the article below that quoted a London magistrate as saying: "The way stateless Jews from Germany are pouring in from every port in this country is becoming an outrage."
Or you can go back much further: there is, after all, nothing new about media hostility to foreigners. In 1905, when the first UK immigration law was passed, one newspaper referred (in an editorial, no less) to "the dirty, destitute, diseased, verminous and criminal foreigner who dumps himself on our soil".
The piece that I wrote last week, citing some statistics about current migration trends, has attracted considerable comment on social media. (More than 120,000 people have indicated that they agreed with it, although of the several hundred who commented on Huffington Post, the vast majority were critical. You can read their comments here.)
Some people interpreted my article as implying that I think all migrants should automatically be allowed to enter Britain, no questions asked. So, for the sake of clarity, I should emphasise that this is not my position. But nor do I think that they are all scroungers or jihadi terrorists.
Many of them - none of us knows how many until they have all been individually assessed - have escaped from the most appalling hardships in their home countries, and have then risked their lives on the long and arduous journey to Europe. Many have also paid thousands of dollars to people traffickers, so it's scarcely surprising that they are determined, by whatever means possible, to get to their chosen final destination.
The nearly a quarter of a million people who have arrived in Europe this year represent a massive headache for the authorities in both Italy and Greece, who are desperate for more help from their EU partners. And don't forget the nearly four million people who have sought refuge from the Syrian civil war in Turkey, Jordan, Iraq and Lebanon.
All of which prompts the thought that the real scandal is not how many people are huddled in Calais hoping to get to the UK, but how few we are allowing in.