Ah! Steerpike can probably speak with more authority on this than I can, but I believe the answer is yes, you are certainly allowed to publish a book in English as a non-native-English speaker. There are many books like that on the market.We discussed this in the chat the other day. My memory is a bit hazy, but as far as I understood it at the time the question was: "Am I allowed to write/publish a book in English even if I'm not a native English speaker?"
I could be wrong though.
English is not my primary language, is there any publishing rule against publishing a book written in English?
If there is, Joseph Conrad would be an unknown Polish author.