There was a bunch of people who lived in a country, quite a long way away from here, in an easterly direction. They lived in peace with their neighbours, worked hard, loved their families and followed their religion.
Then the people who ruled the area, decided that this wasn't good enough. So they made rules that allowed them to live only in certain places, because they didn't want them in the rest of the country.
But then the people in charge decided that they didn't want these people there at all. So they encouraged the harassment and killing of them, which was made easier by the fact that they were all collected together in a small area. Naturally, the people who were suffering this, wanted to leave. They thought about where they'd want to go, and a lot of them decided "England", because England has a long tradition of tolerance, England is a civilised country, and in England you stand a chance of making a new start.
Of course, when the trickle of strange-looking people speaking no English, became a flood, there was some resistance to that immigration. But the resistance wasn't so strong that it prevented this exodus.
Which is just as well, because if my grandparents hadn't left Poland for England in 1905, they would have been killed by Hitler in 1943, and I wouldn't have been born.
Now ask me my views on immigration from the Middle East and North Africa to England..