I kind of use that “would I pull out my laptop” question as a guide to mobile phone politeness. In any social context, if it would be rude to pull out a laptop and start typing, then it is also rude to pull out your phone and use it. Rule of thumb, there may be exceptions.
BBC app is awesome it could be way more awesome when using a smart glasses but we don't have them yet. I'm waiting for that day... :)