The chief executive of troubled rail firm Govia Thameslink, which operates the Great Northern and Thameslink lines, has resigned.

Charles Horton said: “I recognise that passengers have been hugely frustrated at the significant disruption caused by the introduction of new timetables.

“It is the right time to hand leadership of Govia Thameslink to a new pair of hands.

“I am immensely proud of my team and I would like to thank my 7,000 colleagues at Govia Thameslink for all their hard work over the past four years.”

There have been near-constant delays and cancellations since new timetables were introduced on May 20. Govia Thameslink, a joint venture of the Go-Ahead Group and French firm Keolis, also runs the Southern and Gatwick Express services.

The Go-Ahead Group said Mr Horton would remain in his position during an interim period and oversee the development of a temporary timetable aimed at resolving the disruption.

Go-Ahead Group chief executive David Brown said: “I would like to thank Charles for his hard work with Govia for the past 15 years. Under often challenging conditions, he has built a team to deliver the largest railway change programme for decades, on a franchise that is not only the UK’s biggest, but which has also has seen the highest passenger growth.”

Mick Cash, general secretary of the RMT union, said: “Mr Horton may now have gone but the rotten franchise he was steering remains in place and no change at the top will alter that. This whole basket-case operation is a failure on every level.”