"...But you know what? When I hear a bloody good singer and / or guitarist and look round the room to see idiots flicking through their books deciding what they are singing next, I can't help feeling they have a bit of a nerve. Anyone would think the whole bloody pub is eagerly awaiting their next rendition of Wild Mountain Thyme....">

I agree 100%.
I hate when people prep their next song or check their emails/facebook when someone is singing. It is totally disrespectful. Wait till the song is finished then do what you have to, you ignoramus.

It would be great to see everybody at a session check their phones en mass throughout the turn of one of these offenders. Maybe then they would get the message.