An emergency brake was used to halt a Caledonian Sleeper train after it overran a platform at Edinburgh Waverley Station on Thursday.

A trade union leader has now called for the "immediate grounding" of the new fleet of Sleeper trains until the full details of what went wrong are known.

Rail accident investigators visited Waverley to gather evidence on the incident.

Manuel Cortes, general secretary of the Transport Salaried Staffs' Association, 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."

The Northbound Lowlander service ended up several hundred yards to the east of the station before being stopped at Abbeyhill junction.

The train blocked a junction, causing disruption and delaying trains to and from North Berwick, Dunbar, Tweedbank and London.

Serco, which operates the service between London and Scotland, confirmed the Sleeper train overran the platform and described what happened as an "operational issue".

A spokesman added that the emergency brake was deployed by the train manager.

He said: "We can confirm the emergency brake is what brought the train to a halt and was deployed by the train manager."

A Rail Accident Investigation Branch (RAIB) spokesman said: "An RAIB inspector was deployed yesterday to gather evidence.

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