Brake valve was closed on overshot train at Edinburgh Waverley station

The train came to a halt 650m east of the station

A brake pipe valve was left closed on a Caledonian Sleeper train which overshot the platform at Edinburgh Waverley, a preliminary rail accident investigation has found.

The Northbound Lowlander service ended up 650m (711 yards) east of the station following the incident on 1 August.

The error happened when the locomotive had been attached at Carstairs.

It meant the only working brakes were on the engine "which were insufficient to maintain control of the train".

Well below normal

The train involved was the 2336 Lowland Sleeper from London Euston.

On its way to Edinburgh it had stopped at Carstairs where a different locomotive had been attached to five carriages.

The incident, which did not cause any injuries or damage, happened at about 07:26.

However, "the outcome could potentially have been much worse, had it led to a collision with another train", the investigation found.

The report said that on the approach to Edinburgh, the driver discovered that the train's braking performance was well below normal.

No control

He had no control of the brakes on the coaches because a brake pipe isolating valve was in the closed position when the train left Carstairs station.

The train was brought to a stand by an emergency device being used in one of the coaches by the train manager, which caused the train brakes to apply.

The full Rail Accident Investigation Branch investigation "will identify the sequence of events that led to the incident".

The inquiry will consider:

• How the isolating valve came to be closed at Carstairs

• The preparation of the train at Carstairs, including the attachment of the locomotive and testing of the train's brakes

• How the train was driven

• The suitability of relevant procedures and working practices

• The design and approval of the brake system fitted to the Mark 5 coaches

• Any relevant underlying management or organisational factors