According to my sources on the ground (family having a holiday in the area - they went out on the 5th), the outbound service (12th) arrived in Avignon too late for some people to get their hire cars as the hire office (not the one at the station) had already closed.
The staff made a fairly quick turnround (1h15 or so) and the return service got back into St Pancras about an hour late, so family not too inconvenienced.