It was a Loud native that failed Mrs. Catcher's motor in Drogheda, Hal. Told me he had one of them himself so knew them pretty well which would explain how he spotted the auxiliary bulbs. He did helpfully explain why the sills rot where they do though, pointing to water ingress behind the wheel arch liner. With that in mind I filled the repaired sill end with some X8 (similar to Tec7) I had in the shed so it shouldn't recur.