Firstly, I'd like to offer our sympathy to all those involved in this latest sad incident.
I was affected in that I arrived at Bristol Temple Meads in time for my 16:53 return journey to Nailsea & Backwell - and the train arrived on time. However, we were already hearing station-wide announcements that an incoming Cross Country service was arriving after a considerable delay "due to a person hit by a train", so things were clearly not good.
We boarded our train (a crammed two-car 150) and I saw the relief driver as he boarded the cab. He then popped his head round the vestibule door and (in a broad Scottish accent) told us in the front of the first carriage that we wouldn't be leaving any time soon as he didn't have a conductor, due to that earlier incident - but he'd let us know as soon as he'd found one. He then made an announcement over the public address system to the whole train to this effect.
Within some ten minutes, our conductor arrived - having been delayed by the disruption caused by the earlier incident. We were then on our way.
I offer this as an example of how a little basic communication can help in such situations: even those who were weighing up the possibility of switching to a later service, so as to (ironically) arrive on time further west were reassured, and stayed on board.
Well done to our First Great Western train driver in today's sad situation.