i have seen what immigration has done first hand too!
for example the irish workforce that came over build most of the tube system that in london (that had there counrty stolen by the british empire) (granted its always falling apart lol)
the west indian community (also had there country stolen by british empire i might add) came over in the 60's add most of the women became midwifes and helped delivered alot of the countrys babies
indian people came over (yet again had there country stolen by the british empire) and have helped the economy in several ways alot of this country top doctors and surgeons are indian
did i mention england/britian stole wales, scotland, ireland, northen ireland, india, pakistan, west indies parts of africa , canada, usa etc.....
anyway if you want to moan its up to if it makes you feel better feel free too, theres always going to immigrants who do bad things but that does not mean that all immigrants should be tarred with same brush.