[nick_dm]

It doesn't surprise me that learning from movies and the internet would make you more proficient than someone who learnt by living in the UK. When people are forced to speak a language that they do not know well they often end up reinforcing bad habits. Once someone has developed bad pronunciation or inadvertently trained themselves to ignore certain grammatical features it takes a lot of effort to correct the habits. Of course a committed learner can offset this to some degree, but most immigrants aren't willing to put in the effort and are only partially aware of the mistakes they are making. After three years they then speak in much the same way as they did after six months, but with a larger vocabulary.