English language students visiting the UK for any length of time will quickly notice that many native speakers don't follow the rules of their own grammar. But as Anna Kapica-Harward, who moved to London a few years ago, argues, failing to follow grammar rules does not mean that you don't know them.
What would you think if, after years of studying English, you arrived in Britain and heard lots of native speakers say, "I didn't have no idea you was in the pub yesterday"?