The announcements on the 06:42 from Hereford allegedly said that the delay was due to carriages without lights, though they still weren't on later in the journey - passengers were not allowed in those carriages.

At Kingham, the information screens were having a bit of confusion earlier in the morning: I arrived there at 06:20 to see a train leaving, next to a display board saying that the 06:24 was on time.  It turned out that that was the train before, running late rather than the 06:24 leaving early.  The 06:24, then variously was announced as on time, disappeared from the boards (and realtime info claimed it had already left) then reappeared as running late. 

Full credit to whoever put on the extra stop at 07:03 though, to catch some of the traffic that should have been on the cancelled 07:20, which caught even more of that traffic thanks to its late running.