An investigation has been launched after a Caledonian Sleeper train was forced to make an emergency stop when it overshot its platform at Edinburgh Waverley station.

Staff on the northbound Lowlander service activated the train’s emergency brake to bring it to a halt several hundred yards past the platform on Thursday morning.

The train came to a stop across a junction on the line, blocking services to London, Dunbar, North Berwick and Tweedbank, before it was pushed back to the platform.

Serco, the operator of the Caledonian Sleeper, said it believes the fault was “an isolated operational mistake” rather than a technical issue with the train.

The Rail Accident Investigation Branch (RAIB) immediately launched a probe into the incident, with inspections of the scene and the train being carried out to determine the cause of the out-of-control vehicle.

A spokesman added: “An RAIB inspector was deployed yesterday to gather evidence.

“We will use this information to decide any further course of action.”

The incident sparked calls from a transport union boss to stop using the newly launched trains, which were introduced from the end of April and have suffered numerous problems and votes for industrial action from staff over working conditions.

Ryan Flaherty, Serco’s managing director for the Caledonian Sleeper, said: “We are very proud of our train manager who followed the correct processes and deployed the emergency brake to bring the train to a stop during yesterday’s incident at Edinburgh Waverley.

“Our own early investigation indicates there are no technical or safety concerns with the rolling stock and that this was an isolated operational mistake.

“Following the incident, our new trains ran as normal last night and will do so again this evening.

“We will continue to work with the relevant authorities to investigate the underlying cause and expect to provide an update next week.”

TSSA general secretary Manuel Cortes said: “Clearly this is an incredibly serious situation which calls for nothing less than the grounding of the entire new Sleeper fleet until we have the full details of the what went wrong.

“No-one should be playing fast and loose with faulty brakes on our railways and Serco need to wake up to that fact and act now.”

Robert Samson from the independent passenger watchdog Transport Focus said: “The safety of passengers is paramount so Transport Focus wants a full investigation of this incident and for Serco to publish the full results of any investigation very promptly.

“Any recommendations and lessons to be learned must also be implemented to ensure such an incident does not reoccur.”

Scottish Liberal Democrats spring conference 2015
Liberal Democrat MP Christine Jardine (Andrew Milligan/PA)

Edinburgh West MP Christine Jardine called for a “swift and thorough investigation” into the “extremely serious situation”.

Ms Jardine said: “As a regular passenger on the Caledonian Sleeper service, I was very concerned to hear about the incident at Waverley station yesterday.

“It’s especially worrying given how crowded the station and trains are at the moment for the beginning of the festival.

“I’m thankful that no-one was hurt but it’s an extremely serious situation and I hope that the operator, station and rail accident branch work together to carry out a swift and thorough investigation to ascertain what caused this incident as soon as possible.”