I believe the problem was a ‘wrong side’ signal failure - when a signal displays an aspect or gives an indication that is less restrictive than it should be. Thorough testing required when that sort of thing happens. Not sure if it’s connected with the upcoming resignalling?
Oh well; can't blame Jeremy Corbyn - he was, er, elsewhere - as usual.
......did he hear a rumour that Chuka Umuna might turn up? 🙂