FIRST Minister Nicola Sturgeon has unveiled the new look exterior of the new Caledonian Sleeper franchise, which is set to transform the famous cross-border rail journey into a "hotel on wheels".

Ms Sturgeon was in Inverness on Monday to launch the the service's new White Stage branding which will become a symbol of the new Sleeper under the 15-year Serco franchise, which is due to begin on April 1.

The Scottish Government took the decision to create a standalone Sleeper franchise separate from the ScotRail umbrella for the first time as part of an ambition to revamp the overnight London-Scotland service into "a tourist rail experience to rival the best in the world".

New operator, Serco, also runs Australia's iconic transcontinental India Pacific service, linking Sydney and Perth, and the Dubai Metro.

Ms Sturgeon said: "When the Scottish Government set the specification for the re-franchising of the Caledonian Sleeper service, we were clear that it had to become so much more than a commuter rail trip for those travelling between Scotland and London.

"We knew that the routes through Scotland already offered a spectacular backdrop, but we wanted to see the journey become a destination in itself and take a larger tourism role in promoting Scotland.

From next week, Sleeper passengers can expect a new on-board catering menu which promises to "showcase the best of Scottish food and drink", refreshed accommodation, toiletries, and new aeroplane-style sleep kits, including eyemasks and earplugs.

In the long-term, the contract includes a £150 million spend on 75 new state-of-the-art carriages, which will combine to make up four trains. Manufacture of the new rolling stock - designed by CAF, the Spanish firm behind Edinburgh Trams - is set to get underway later this year with the fleet coming into service from 2018.

The new new trains will offer passengers a choice of cradle seats, pod flatbeds, standard class berths or en-suite berths in first-class. There will also be a brasserie-style club car for dining and the option of viewing films and television via free wifi.

Ian Smith Design, the Edinburgh-based interior decorators who overhauled the bar and restaurant of Andy Murray's luxury Cromlix hotel, will also oversee the revamp of the Sleeper's decor and railway lounges.

Ms Sturgeon officially opened the new Guest Service Centre for Caledonian Sleeper passengers at Inverness on Monday. The passenger lounge feature soft furnishings and shower facilities.

New staff uniforms have also been designed by award-winning Glasgow fashion designer, Alan Moore.

Rupert Soames, Serco Group Chief Executive Officer, said passengers travelling overnight from next Tuesday into Wednesday would be the first to notice a difference.

He said: "As a regular user of the service, I know that for business and pleasure it is both an efficient and an enjoyable way of travelling between London and Scotland, allowing you to have whole day's extra work or play on each return visit.

"Serco is well on the way to transforming the Sleeper into a superb service using our expertise of delivering high quality transport services around the world. From the March 31 our guests will see the service get better and better, with a new booking website, branding, uniforms and a menu that showcases the best in Scottish food and drink."