A spokesman for Northern said: "We welcome the ORR's findings on Northern and are reviewing the detail of the investigation report.
“Last year was very difficult for our customers for well-known reasons, particularly the ongoing impact of delays to infrastructure upgrades. This meant we did not meet people’s expectations and we are sorry for that.
“Following the experience of 2018 Northern has made improvements, and we continue to invest in better customer information systems and processes. We are determined to deliver a better service for our customers in 2019 with improved punctuality, the delivery of new and refurbished trains, and better stations."