While saying that all the people who voted "leave" are racist is wrong, a part of them are. To me, blindly assuming that "immigrants just leech" with no shred of evidence is racist, as an example (no proof == prejudice == racism by definition - as racism is prejudice coming from racial difference).
I'm pretty sure in the UK (like it's in Italy) migrants can only apply if coming from countries in war (and let's not forget that we are at the origin of most of those wars, if not all), or if they're able to find a job and work (and they're often exploited for jobs no one else would do).
And since terrorism was mentioned earlier in the discussion, let's take
the data that some user posted. On average it seems 160 people or so get arrested every year for religion-motivated terrorism in the whole of Europe (of which, a large part is in France).
More than 1,3 million people sought asylum in Europe in 2015 (with 1,800,000 estimated to have crossed the borders).
Only a small part gets accepted. Now, assuming that those 160 people are all muslims, they all get convicted (arrest != conviction) and they're all migrants (which is already false, since a lot of the perpetrators of the Daesh attacks were European citizens) it's 160 against the millions of migrants in Europe.