I agree with you that it is highly offensive, I would be incensed if someone said that to me about my culture like that.
But TBH, he was not talking about your race, he was talking about what he considers to be the more uptight characteristics of English culture. That doesn't mean he is racist, being racist is different to that.
For instance, there are things within my own culture's (I have more than one), that I do not like. But I am not self loathing of my race, I just don't like those particular things about my culture's.
Racism is more about hating on the basis of genetics as opposed to culture, and the belief that one race/ culture is somehow superior to another.
I would say he doesn't like English culture, but is not racist. He may not like English culture but that does not mean he doesn't like English people IYSWIM. I guess it is more the sense of superiority thing I am thinking of too, like disliking English culture may not mean he thinks it beneath him, just not what he likes.
If it was just an outright hate of English culture and/ or people, I would call that racism. Or if he had preconcieved idea's of English people or culture that were very negative and/ or painted English culture as beneath his, I would also see that as racist.
But he doesn't have to like English culture, it doesn't necessarily make him a racist, it is more about the extent to which those feelings run IMO.