Oh hell. From this thread I have learnt that I have probably offended the new member of staff in my local shop 
She has the most gorgeous accent and I told her so and asked where it was from. Turns out Poland. She was telling me how she came here to be with her DP and that she finds the people really friendly. I live in a poor bit of Yorkshire, and was amazed that someone would leave such a beautiful country as Poland to live here. I asked her so many questions as she was lovely and chatty.
I now feel a right pillock that I was probably getting on her nerves by asking her. There was zero malice behind it at all, she had such a beautiful voice and I was being nosy. I see now how irritating it must be.
Do cultural differences within the UK add to this? In Yorkshire, everyone talks to everyone else. We are incredibly nosy about differences and really like to find out about people. I suppose if you haven't been brought up here, or have an accent, it must seem so nosy and intrusive. But we also would undoubtedly comment on someone having amazing pink hair, or a stunning tattoo, or a beautiful complexion etc irrespective of a person's heritage. We are interested in everybody.
Obviously, I won't ask questions any more as I would hate to offend and the tedium and "othering" of it never occured to me. I suppose because I live in an area where we are largely proud that immigrants would choose to live here, so it certainly isn't a "go back to where you came from thing"
One question which I have (please don't verbally kill me, its a genuine question which I am puzzled about): is there a point at which there is a parity between the cultural practices of the area a person lives (so the people of Yorkshire being chatty and nosy buggers), and the rights of people who choose to live here to not be asked questions? So if most people in an area are interested in each other and that's a cultural thing, at what point does that become something that should be tolerated by someone moving here?
I worded that REALLY badly, but I hope you know what I mean. Apologies for any offence caused. I am very bad at wording things.