//I'm not bothered if she's locked up for a very long time, but she was raised in Britain, she gained her beliefs in Britain, and that to me makes her a British problem, not a Bangladeshi (or other) one.//
There are many, many undesirable people in the UK, most of whom we cannot rid ourselves of. This one we can. She upped sticks and went elsewhere and has been denied re-entry. Quite why we should want to see her back here because it is where she was raised and gained her beliefs is a little mysterious.
This country (along with a few others) needs to understand that it cannot cure the world's ills. There are places in the world that are beyond redemption and some people in them that are likewise. This woman is one of them and we're best off without.