Over-running engineering works have caused chaos for tens of thousands early morning commuters heading to London at the end of Bank Holiday weekend.
Services running from King's Lynn in Norfolk, Cambridge and Stevenage in Hertfordshire were all affected.
First Capital Connect has put in place a reduced emergency timetable after dozens of train services were cancelled during the morning.
Network Rail was working on the line at Alexandra Palace in north London over the weekend and there were problems discovered after testing.
Click below to watch a report by ITV News Anglia's Olivia Paterson
More top news
Brightening up after a dull start with most parts staying dry. Top temperatures of 25 deg C (77 deg F).
Hundreds of people have attended the funeral of a motor cyclist from West Norfolk, killed in a race in Hampshire earlier this month.
Five people have been arrested after a teenager was stabbed in Ipswich and left needing intensive care