Train drivers who do not have to work on a Sunday will soon be contractually obliged to do so.

Govia Thameslink Railways (GTR) have vowed to improve the service, which currently sees one in six trains cancelled.

The line runs through stations including Hendon, Mill Hill, Borehamwood and Radlett.

It says from October, as part of an annual pay reviews, drivers will have to work a limited number of Sundays.

This means 12 Sundays a year for those employed after June 12, 2017, and eight a year for those starting before.

GTR’s local development manager Larry Heyman said the change would make the service a lot better.

But Hertfordshire County Council's councillors are concerned it has taken so long to bring in Sunday working for drivers.

Cllr Steve Jarvis said: “I am incredulous that apparently drivers don’t work weekends if they don’t feel like it at the moment.”

Panel chairman Cllr Derrick Ashley – who plans to raise the matter with the Department for Transport – said: “Four years on from the franchise still not to get better cover on a Sunday is incredible

“It does seem ludicrous that there are terms and conditions that should have been changed on 2006 that still haven’t been changed.”

Officials from GTR had come to talk to the panel in the wake of the the Rail Plan 20/20 timetable changes, that were introduced in May.

When GTR introduced the Rail Plan 20/20 timetable changes they claimed it would be the biggest transformation of UK rail network in decades.

It said it would mean simpler and more reliable journeys – with an additional 400 trains a day and space for 40,000 more passengers into London a day.

But instead there was a serious drop in performance – with passengers in Hertfordshire frequently complaining about cancelled trains, lack of seats and fewer peak time services.

At the meeting of the county council’s cabinet panel Larry Heyman, GTR’s local development manager apologised.

He said: “If we look back to May 2018 I can only start by making a huge apology for the fact that things went so drastically wrong with the launch of the timetable.

“The number of cancellations and the fact the timetable just didn’t do what it was supposed to do was immensely disappointing for our passengers, immensely disappointing for the people who work for us.

"I personally felt a combination of disappointment and embarrassment.”

An additional wave of changes, that had been planned for December, has now been delayed.

But there will be some additional services from Harpenden and Letchworth.

Meanwhile Cllr Steve Jarvis called for greater information so passengers knew earlier if services were cancelled or platforms changed.

He said: “Passengers are incredulous that you don’t know five minutes before a train is due to arrive that it’s not coming.

“This has a significant impact. People need to plan their working lives and childcare arrangements as well as just getting somewhere at a particular time.”

Cllr Sara Bedford said information about platform changes was so late that some passengers – particularly those who have difficulty walking – couldn’t make the train.

Mr Heyman accepted that the speed of information was “not acceptable”. He added front line staff were as frustrated by it as passengers.