TRAIN services run by a strike-hit operator have plummeted to their worst levels since a watchdog began monitoring performance.

A report published by the Office of Rail and Road (ORR) found Govia Thameslink Railway (GTR) services had deteriorated over the year.

The independent regulator gives quarterly and annual performance scores based on how many trains arrive within five minutes of schedule for short journeys, and within ten minutes for long-distance trips.

It also records the proportion of trains arriving late or significantly delayed.

The company’s annual average performance score of 78.8 per cent was the lowest score recorded since 2004.

The watchdog revealed passengers faced cancellations and significant delays on 6.7 per cent of journeys between January and March.

GTR is the parent company of Southern, which continues to be in a dispute with drivers and conductors over the introduction of driver-only trains on the network.

The battle, which has been running for more than a year, has led to thousands of passengers across Sussex experiencing delays and disruption.

Members of Aslef recently rejected a deal drawn up by union leaders and Southern bosses to bring an end to the dispute.

The Rail Maritime and Transport union (RMT) is continuing to negotiate with Southern to try to come to an agreement.

A GTR spokesman said: “Passenger numbers have doubled in the past two decades and we’re involved in a massive modernisation programme to address capacity, congestion and punctuality on our network.

“Our punctuality has improved five months in a row and stood at 83.9 per cent of trains on time for the four-week period ending April 29.

“There’s more to do so we will continue to upgrade and modernise our systems and service to improve our passengers’ experience now and in the future.

“To help achieve this, we are working closely with Network Rail onits £300 million package to improve reliability across our network.”

RMT general secretary Mick Cash said: “This is yet more shocking evidence that confirms everything passengers know about the performance of GTR day in and day out. The only serious solution is public ownership.”