I do take my phone out with me. If I'm with a friend or family when it beeps. I say ill, just look at this quickly. If needed immediate response I'll text back. If not phone gets put away until I can respond. As a childminder I sometimes get texts from parents about a school activity. I reply so they know I've seen text. Think it's very rude when someone constantly looking at phone whilst in company.
To think that London, or anywhere else for that matter, does not belong to any one demographic