Officially the runway edge lights at Cardiff were a bit wonky. They lost one phase and the Thommo captain used that as the reason to divert.
The more cynical of us decided it was because we had an early morning Thommo flight this morning and Cardiff didn't (so we found out) and that the crew were possibly going to be too short of hours to position over to BRS ergo land at Briss and bus the cattle over the bridge. Job done.
Airlines eh, don't you just love them!?