The company running Welwyn Hatfield’s trains has been ordered to pay more than £13million as punishment for prolonged disruption in other parts of its network.

Govia Thameslink Railway has described the figure of £13.4million, set by the Department of Transport for cancellations and delays on its Southern services between September 2015 and September 2016 as “fair”.

In his letter, Secretary of State Chris Grayling accepted some of the problems had been caused by strikes, and performance had “dramatically improved since Christmas”.

But he told the company: “Performance is still not good enough. I know you accept the need to further improver services for passengers.”

The company has to provide a “remedial plan” showing how it will spend the money to improve train services, although £7million will be allocated by the Government to “directly benefit passengers”.

Chief executive Charles Horton said “We are pleased that this issue has been concluded, and accept and are sorry that our service levels haven’t been good enough for passengers.

“We run the most congested network in the UK where passenger journeys have doubled in the last 12 years.

“This has meant we have been running services for more and more passengers while also allowing stations to be rebuilt, platforms extended, track and signalling replaced and new trains and technology introduced too.

“The impact on the network of such extensive work was underestimated, but as the recently-published Gibb Report makes clear, the most significant factor affecting Southern’s service levels has been industrial action caused by the trade unions.”