The Rail, Maritime and Transport (RMT) union confirmed this morning that members had voted for both action short of a strike and strike action amid a dispute over staffing, workloads, and training.

Serco, which operates the Sleeper service, has seen the launch of a new £150m fleet beset by problems, with the threat of strike action coming as a further blow.

RMT officials said members voted for industrial action by a margin of more than ten to one with a turnout in excess of 80%.

Strike threat to new fleet

The RMT executive is set to decide on next steps, with urgent talks between the union and management likely.

RMT General Secretary Mick Cash said: “Our members on the Caledonian Sleeper are sick and tired of paying the personal price for the botched introduction of the new fleet and that is why they have delivered this overwhelming vote for action.

“It is time for SERCO to wake up and take note of the appalling working conditions their mismanagement has lumped on their staff and to take action to resolve this dispute.

“The result will now be considered by the union’s executive and we remain available for genuine and meaningful talks.”

Ryan Flaherty, Serco's managing director for Caledonian Sleeper, said: "We're deeply disappointed by the result of the ballot.

"I believe we have shown a real commitment to dealing with the issues the RMT has raised and indeed there was an acceptance on all sides that progress was being made.

"We remain open and willing to engage in further talks to avoid industrial action and are fully committed to delivering the best possible service to guests."

Caledonian Sleeper staff vote for strike action over 'appalling' working conditions