I will try and be as rational as possible on this very complex issue, but here are my views. I mostly want to 'test' them with people so it'll be interesting to hear feedback. I will, however, be brief because I don't want to write an essay.
1) People have to speak English in England, forget the culture argument, we have to be able to properly communicate. The reason it is offensive not to learn English is because it indicates an unwillingness to even communicate with the current population; showing that their goal is only material.
2) Natural consequences of mass immigration are 'hubs' of a certain community. This is evident everywhere in the world, and yes, including English 'hubs' right across the world whether it is Spain, Germany or India. People naturally seek comfort and security. My girlfriend recently moved to England to be with me, she is yearning to meet people from her native country because people just get home-sick; I know I would be the same.
3) However, these hubs aren't a good idea. Mass migration is a negative policy. Immigration is great, we import and export ideas. Mass immigration, however, allows large influxes to move and build a large community rather quickly. This means instead of the cultures of Scandinavia, South Africa, Pakistan, Brazil and so forth, being weaved into society they become blocs. Not because they hate British people, but because of the point raised in 2). The consequence of these hubs are segregationo and alienation. We soon see that natives resent these communities, which mean no harm. We percieve them as "keeping us out" when really all they want is to "keep a little bit of home with them". We turn on them, they turn on us, "our" community begins to reject them and "theirs" begins to reinforce itself. After a few years we have a designated area where "you go" and "they go"; languages seperated and all. The end result? Tension.
4) So even though no harm is ever meant, tension is the result. Neither side can be told they're wrong; it's not wrong for the English to not want to see "no go areas" and likewise it's silly to say to a foreign "when you come here, you leave everything behind..." The only way around it is to ease migration and to allow both foreign communities to retain a little of their culture just so they don't have to let go of everything - I mean that's fair right? I know if I went to, say, India I wouldn't want to just abandon everything English and forget who I was. At the same time, it's fair for the English to say, how about you share in with us too since we don't want to see ours eroded, just as you don't want to lose yours? Culture has to be weaved in, not dumped in huge chunks. Mass migration is not a culturally sustainable policy.
5) Whether or not you think people who react to this issue are bigots or fascists or whatever, you have to accept that a divide is being drawn. In the last election 1 million people voted for BNP; that's terrible. Closing our eyes and simply saying "nope, you're an idiot" doesn't help 1) the people of this country who do feel slighted and 2) the people who have come here with their families who are now under seige!
6) England has a culture; to suggest otherwise is silly. I feel that our culture is probably stronger than most other Europeans. I mean look at us! We're ridiculous (in a loveable way), our lawyers and judges still wear wigs, we crave tea for no real reason, we love our biscuits, we eat 1 meat 2 veg. We are a nation of people who are very calm and sit back and say "ah, the world is changing - we better see how this plays out before I decide what to say"; sometimes to our detriment, i.e Europe (we have to acknowledge that a Non-European economic policy in 2012 is like having a colonial foreign policy nowadays). The furniture we buy, the paintings we like, the T.V, the humour, the way we dress, the fact that we secretly say "oh that's ok" while thinking "God I hate you SO much!". I never really noticed we had much of a culture until I met my girlfriend and she would mock me for it. Her most used is how we say "If I may, could I please..." etc. It's the small stuff, the stuff we don't notice because we're living it - it's hard to have an objective view in a subjective matter.
7) The Human Rights Convention (and subsequent UK Act) is an amazing achivement. British lawyers had easily the heaviest role in drafting it. It reflects our values to the t, individuals are equal. There is no "oh let's sacrifice him for the common good", we say no, everyone is equal under these laws. Having it in a supranational court enables proper independent perspective. It also very rarely intervenes, in 2010 out of the nearly 2000 applications for review submitted, only 23 were head; only a handful disagreed with the UK. Sometimes cases aren't what we want to hear, like Qatada. However, we have to be morally above such people and cannot say "ah well, screw him!" and say "yes, you hate us but we wont turn our back on another human" and ask Jordan why it tortures people to obtain evidence - that's wrong and it's a principle I want to uphold, whoever it targets - bad or good. Sometimes challenges are tough, it means we evolve and learn from them; we can deport Qatada legally with proper assurances of a fair trial (MOUs), this is how we should pursue - if we want to maintain our claim to integrity.
8) last point. If the world submits to a concept of mass migration we will lose individuality of nations. One of the biggest reasons for the growth in ideas is because of the power of distinct 'individuals' passing their views. When Europe met Asia we exchanges ideas and we both created fantastic things, we swapped those ideas and so forth. If the world becomes a mash of different groups who are no longer distinct, there is no originality in thought; no differing perspetices to offer an "outside view" and inject an entirely different concept.