I avoid quiet coaches if at all possible, the tense mix of very occasional antisocial behaviour with the predictably uptight usual occupant is very irritating and puts me off my work more than phone conversations or the bish bish bish of headphones turned up too far.
There was a particular incident a few years ago that finished me off with the sorts of pompous self righteous geriatric that tends to inhabit Coach K on what was East Coast at the time.
I had to make, not take, two calls between Newcastle and Edinburgh. Both times I left my seat and moved to L, in other words there were two sets of vestibule doors between me and the precious quiet coach. I didn't even want to be in quiet, that's what the booking system gave me.
A ticket check occurred just after I returned to my seat for the second time. An elderly passenger one bay away from me thrust a quivering finger towards me and said 'this is the third time this month that people like that have been getting up and down to make calls, you have to do something about it'. The guard was great, she just said 'well, maybe we need more quiet coaches sir'.
So he was upset by the idea of someone on the phone on a train, not that he was directly disturbed by it.
I think some people need to get out more, and most of those people generally choose the quiet coach.