Sorry about the Albanians they probably got into the U.K. the same route as some Russians I have met entered on Polish passports, we really need to sort our borders out
Turn about is fair play. 
We’ve had people from the right hand side of the Atlantic explaining just how we should be handling race relations since the 1950s with a LOT of tongue clucking (and a fair amount of “We do it better!”) during the 1960s.
The “mass immigration is relatively new” is not true for Spain, Italy, France, Portugal, the UK, Flanders… unless you think that the last, oh, 1500 years count as “relatively new”. For example, my home town of Pamplona used to be divided into three walled cities through the Middle Ages, each with its own laws and customs, and one of the three was immigrants from North of the Pyrenees and their descendants, what we called francos. The three towns became one in 1423 but the walls stayed in place for centuries. Scots-Irish are Scottish people who descend from Irish folk that stopped in Scotland while in their way to America; my own Italian forefathers did that on their way to Argentina, but in Barcelona rather than Glasgow. The Napoleonic Wars left French lastnames strewn all over Europe, but so had the Revolution. Refugees are as old a phenomenon as wars.
Monolithic in terms of culture and ethnicity well, we tend to come in shades of white, but you’re discounting the homogeneizing effect that massive schooling and television have had on cultural aspects. There are dialects separating into languages even now, but for the last two hundred years (that is, since the idea of “nation-state” came into play) the tendency was for dialects and for minority languages to get rolled over. Speaking French or Spanish or Italian wasn’t enough: in order to have any kind of career you needed to learn “acceptable” French or Spanish or Italian, and everybody on TV had the same accent. This is rolling back in some countries and for some languages, still very much in evidence for others.
Where I live, locals are a minority. Somehow we survive, despite the constant horror of leathery old bodies in thongs and Speedos.
Oh God, Mighty Girl… I just had a flashback of being a teenager and dealing with rodrígueces who thought the absence of their better half meant permission to become Don Juan… (rodríguez: a dude who’s stayed in town while his wife takes the kid to the seashore). You guys get that multiplied by twenty thousand.
What’s happening in Europe is more about a particular branch of a religion rather than race. I grew up in very multicutural town, so it’s all I’ve known, but this particular branch of Islam is causing problems. I know in your liberal wonderland we’ll all be great friends and neighbours, but if you don’t mind me quoting Churchill about another differing menace: " if we fail, then the whole world, including the United States, including all that we have known and cared for, will sink into the abyss of a new Dark Age, made more sinister, and perhaps more protracted, by the lights of perverted science."
I agree with you It is not until you visit some of the multicultural towns in the U.K. where there is an Islamic population that you have an understanding of the problem. Where I live we have a 16% immigrant mix but no Islam and there is not a problem every one gets along