I think someone mentioned it on here, possibly earlier in this thread, that they knew someone whose parents had come to Britain from India "back in the day" and were delighted to be here and to be accepted.
True, there were racist movements in the 60s (well done, Enoch!) after the initial, what you might call "mass" immigration from the Caribbean and the Indian sub-continent, but the people who came, for work opportunities, for a new start, or for refuge (e.g. from Idi Amin's Ugandan atrocities against the Indian people) really and truly integrated, albeit understandably wanting to retain some of their own culture (cf. the John Bull pub in Benidorm).
I lived in Leicester in the 80s and 90s, and it was a great example of multi-culturalism and a real "melting pot" of cultures enjoyed by all sides (even though you might describe the distribution of the faiths and races as being slightly "enclave" in their pattern), mainly first and second generation immigrants.
What i simply do not understand is why their kids and grandkids now consider themselves to have closer ties to their ancestral homeland and culture and to be less "British-Asian" or "Black British" than their parents did 30-40 years ago. I think this is causing increased division nowadays, particularly around gang culture.
Apologies if my being a privileged middle-aged white bloke has caused me to over-simplify the issues.