THE new Mk5 Caledonian Sleeper coaches have continued to be dogged by problems.

It is has emerged that it was wheel flats caused by unexplained brake applications which brought the northbound Lowland sleeper to a halt at Stafford early yesterday. Last night’s service was cancelled as a result, and CAF engineers are now investigating what went wrong.

Passengers were woken to be told that the rest of their journey to Glasgow would be on board rail replacement coaches. Passengers for Edinburgh were advised that ScotRail would accept Sleeper tickets on trains from Glasgow to Edinburgh. On board staff announced that ‘our engineering team is working hard to understand what caused the train to apply its emergency braking system’.

Caledonian Sleeper has apologised and said passengers could also apply for a full refund. The company said: ‘Our apologies to guests but due to a technical issue with the coaches, this service will have to terminate at Stafford. Replacement road transport has been arranged to take guests from Stafford to Glasgow.’

The new fleet should have gone into service last year. The delayed launch finally took place on 28 April but was followed by several setbacks, including a three hour delay to the inaugural southbound service. This was attributed in part to signalling problems, but the franchise owner Serco admitted that there had been faults on board the train as well.

The introduction of the new trains on Highland services has also been postponed from the start of June to 7 July at least.

Caledonian Sleeper managing director Ryan Flaherty said yesterday: ‘As a result of the technical issues, we have taken the decision to cancel tonight's Lowland service from Glasgow/Edinburgh to London. We will be contacting all guests scheduled to travel to inform them of the cancellation and help them with alternative arrangements.’

The continuing problems have also included two other cancelled services and more late running.

The RMT is holding a ballot for industrial action, including possible strikes, in protest at working conditions on board. The union’s general secretary Mick Cash said: ‘RMT has been deeply concerned over reports received from representatives in relation to the introduction of new rolling stock on the Lowlander services.

‘The introduction of these new trains should be a positive move for both our members and the railway industry. However, this could not be further from the truth, with the situation now reaching breaking point. The union has informed the company that it is being widely reported that stress and mental health issues are rife amongst members, as well as members having physical breakdowns and being left in tears at the end of their shift.’