Network Rail have a lot of questions to answer - just why has this happened despite "thorough" testing before lines reopened.
There is no question the work needed doing but they have royally cocked this up. Remember Network Rail are a PUBLIC company too....
Major teething problems with new signalling equipment installed over the Xmas and New Year break - no idea what exactly is wrong, but along with the issues with overrunning work at Christmas - Network Rail have more explaining to do. Southern have been forced to implement an emergency timetable...