It was known for hardly being used at all, mainly because it ran just a couple of times a day, cost a lot, and had a convoluted booking process whereas the Aust car ferry was turn up and join the queue.
I saw it in the flesh, and in several magazine photographs, and it normally seemed to comprise an 86E 41xx from the Severn Tunnel banking fleet, two car carrying wagons, two or three cars (always seemed just one had paid for the sheeting, others not) and a GWR brake corridor coach.
The booking conditions in the early 1960s Western Region timetable page for it had never been updated since it started, presumably in the 1920s. It still had the paragraph about isolating the Autovac, a generation after the last cars with this were made.
