“Dangerous” – that was the word used in a conversation between two members of Great Northern rail staff amid overcrowding at Hitchin this morning, commuters have said.

Aaran Vince said he was waiting for the 7.55am train into London when he overheard the message on a walkie-talkie held by a member of station staff who standing next to him.

“He had a message through on his walkie-talkie from a colleague that the next train is only eight carriages and is ‘dangerous’ due to the amount of people waiting to get on the train,” said Aaran, in a post on the Hitchin Rail Commuters Facebook group.

“The word ‘dangerous’ was used from one colleague to another, and I and other people heard it. Shocking.”

Another passenger posted to say he had heard the comment too, adding that the train was so “rammed” that not everyone could get on at Hitchin.

“Additional stop at Stevenage meant very few or anyone could get on at Knebworth or Welwyn,” he added.

Asked for comment on the use of the word ‘dangerous’ by its staff, a spokesman for Govia Thameslink – which operates the Great Northern and Thameslink lines – said: “This train was busy and uncomfortable for passengers, for which we apologise sincerely. The continued disruption has been brought about by the delayed approval of May’s new timetable.

“We are re-planning how we use trains and train crew on Thameslink and Great Northern to deliver a new fixed, interim timetable in July that will prioritise peak trains and reduce service gaps, progressively delivering improvement.”

The spokesman urged anyone delayed by 15 minutes or more to apply for compensation, adding: “This can be claimed against the original timetable, and there is enhanced compensation for season ticket holders.”

Rail services have been chaotic since the introduction of a new timetable on May 20, with near-constant delays, cancellations and overcrowding.

This morning there were no trains into London from Hitchin between 7.20am and 7.55am – more than half an hour during the morning peak.

Amid clamours for first-class sections to be declassified on the packed Great Northern and Thameslink commuter services, MPs including Hitchin and Harpenden’s Bim Afolami and St Albans’ Anne Main last night sent a cross-party letter calling on Transport Secretary Chris Grayling to have first class opened on all Govia Thameslink trains.

“Declassifying first class would ease overcrowding and serve as a gesture to commuters who have put up with last-minute cancellations and widespread disruption in recent weeks,” the letter says.

“While we are clear that on this mainly commuter service revenue implications should be minimal, we feel it will require your involvement to see these changes put in place until the service recovers to acceptable levels.”

The letter has been signed by 14 MPs from the Labour, Conservative, Liberal Democrat and Green parties. Mr Afolami and Ms Main are both Conservative.

Posting the letter on Twitter last night, Luton South’s Labour MP Gavin Shuker said: “Every seat should be for any passenger.”