Network Rail has apologised for the train delays for commuters heading into and out of London from Hertfordshire, Cambridgeshire and Norfolk on Tuesday morning.
The company was updating signalling equipment over the Bank Holiday weekend but it didn't work as expected after it was tested at the end of the work.
Hundreds of trains were cancelled or ran late and the disruption continued for much of the day.
Tony Raine from Network Rail said there would be a reduced timetable for the evening rush hour on Tuesday but services would return to normal on Wednesday.
Click below to watch the interview with Network Rail's Tony Raine
More top news
A campaign has been launched to improve one of the key commuter routes in the East, linking parts of Essex and Cambridge to London.
Former Pink Floyd frontman Syd Barrett is being a remembered at a special concert at the Cambridge venue where he played his last gig.
The rather cloudy skies will remain over the next few days but it will stay mostly dry. Some fog overnight at the weekend.