Passengers and special guests boarded one of the new trains for its maiden journey between Glasgow and Edinburgh before they are to be rolled out by the end of May.
Built at a cost of £150 million, the new fleet will be the only sleeper service in the world to offer double beds, with further additions including reclining seats, a hotel-style keycard system and onboard WiFi.
The 75 new carriages will be replacing rolling stock built in the 1980s, travelling overnight between London and 40 Scottish stations.
In addition to the new double rooms, passengers can choose solo or twin club rooms with an en-suite, classic rooms with one or two single beds, or reclining seats. The number of accessible rooms, for passengers with reduced mobility, has also been increased.
Prices range from £45 for seats to more than £300 for a superior double room.
Following delays to the delivery of the new fleet Ryan Flaherty, managing director of Caledonian Sleeper, said staff were “beside ourselves with excitement about the launch of the new trains”.
Mr Flaherty said: “The current rolling stock is nearly 40 years old so the new trains come with a whole new level of comfort and facility that the modern traveller expects.
“We’ve changed our approach completely, when Serco took over we realised that it needed to be a hospitality experience rather than just a functional overnight.
“We are blessed with really good staff who offer a really warm welcome, we’ve now a really comfortable, modern train and that’s supported by a really interesting food and drink offer, so actually we are the smart choice for people travelling between London and Scotland.”
He added: “There’s something quite magical about going to sleep at one end of the country and then waking up - whether it’s waking up in the capital in London, whether it’s waking up in the Highlands - it’s just a tremendous experience.”
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