All the councilors are British. Non Brits can't stand for election, non Brits can't vote (so trying to get their vote is a bit useless).
Abitwobbly, since you don't seem to know as you called them the same race and religion, South African and Bengali are two very different groups. Some South African actually are mostly European and are a variety of faiths. Bengalis, originating in an area in India and Bangladesh, are also a variety of faiths, particularly Hindu, Islam, Buddhism, and Christianity. Your desire to paint Muslims, and Bengalis, and a monolithic mass is not in reality - both are made up of different groups and individuals with different wants and needs. All groups are.
I am an immigrant, I come from the States. I am white passing and no one was concerned (other than the Home office) when I came here. Having leave to remain, I have spent most of my time here caring for others (my white British MIL has MS, FIL has a laundry list of conditions, my DH has multiple disabilities) and coming here just before the crash I have spent most of my time here not employed.
I often get the "you are the type of immigrant we want" and "Immigrants like you are fine" from people in real life. Seeing as my employment record can't be what they are talking about and my religion (Me and my DH converted to Judaism) has brought me to wear a noticeable cloth cap and not doing the typical British traditions, and we have far more than the average amount of kids (4), I can only guess what they mean is that they want immigrants who are the white passing, English speaking, not different enough to cause any qualms, and keep to themselves (caring means I spend most of my time in my home) because that is the me that they are talking about and approving of - when I bring up the that I am most of the things they complain about, I get the "but you are different". Guess what is?
Keeping to ourselves is often what we are attacked for, going out and engaging often means dealing with a lot of harassment and abuse. My kids have had mums pull theirs away when they see me or my DH with his full ginger beard. My kids have dealt with strangers, including Brits drunk in the middle of the day, following us around and shouting abuse (one very traumatic one was a pair shouting Jesus and Mary and a lot of swears at us with our small children there around a shopping area and no one doing anything about it). And we're white, what my British back generations black friend Nic goes through makes my blood go cold and my immigrant friends who are not white even worse.
This is a major part of the mini pockets not just because it is easier to get wanted products and services, but because we need insulate ourselves against abuse, and (repeated studies have shown this) estate agents will show someone not from the White Brit majority housing in those areas far more often even when they can afford to live elsewhere. You don't like it, challenge the systems of oppression not dump hate.