Polish start speaking English. They have a fluency but it sounds very formal and awkward to me.
I think that may be because they learned their English in class, rather than in the real world. My husband spoke no English at all beyond hello, goodbye, please and thank you when he came to Ireland thus his English which he learned initially through conversation and listening to radio and television is very idiomatic and rich in both Hiberno-English and British English influences. He now finds it easier to express himself in English than in Polish!