IT is widely regarded as one of the world's most dramatic and scenic train journeys, made famous as the passage to Hogwarts in Harry Potter.

But plans announced five years ago to transform the passenger experience with "scenic trains" on the popular West Highland Line and other key tourist routes have fallen behind schedule, leaving ScotRail racking up undisclosed fines over the delay.

Travellers on routes to Oban, Mallaig, Kyle of Lochalsh and Dumfries had been promised food hampers on tablecloth-covered tables, learning about the passing landscape from expert guides and offered seats in a "premium carriage".

Themed events were to include Harry Potter "with locally brewed 'butter beer'".

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The Scottish Government's agency Transport Scotland said financial penalties "continue to accrue for failing to deliver this committed obligation", but the cost to date has not been revealed.

ScotRail had also pledged that a tourism ambassador would be on every train from December 2017 - supplemented by multilingual students in the peak season - along with services to Wick, Thurso and the Borders.

The rest of the package, unveiled when Abellio won the ScotRail franchise in 2014, was due by last December. ScotRail was unable to say when this would happen.

It said a "Great Scenic Tasting Box" was due to be unveiled this week that would feature an "exceptional range of food and drink from throughout Scotland" including cheese, chocolate, whisky and gin.

The train operator said it had also "upskilled our hospitality team to a tourism ambassador level of service".

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A ScotRail spokesperson said: "We are committed to enhancing the customer experience on our scenic routes and we are working with Transport Scotland to add to an already fantastic service."

The 164-mile long scenic West Highland Line takes in Britain's highest mountain, Ben Nevis, the UK's largest loch in Loch Lomond, the deepest in Loch Morar and the highest mainline station in Corrour.

Campaigners said passengers were too often having to to put up with a disappointing service.

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Friends of the West Highland Lines chairman Doug Carmichael said: "The eventual arrival of the tasting box sounds very enticing.

"But to those who travel on trains with the trolley service missing from many services because of staff shortages, somewhat cynically, it will be a 'wait and see' how this is managed and operated on what are now over 30-year-old, past-their-sell-by-date trains."

A Transport Scotland spokesman said: "Once fully delivered, the scenic trains package will enhance the passenger experience."

The latest troubles for the line come after local businesses expressed dismay at plans to close a 40-mile stretch between Spean Bridge and Crianlarich between October 5 and October 14, at the tail-end of the tourist season.

Network Rail said it is necessary to carry out "critical work" to replace the track and decking over the Horseshoe Curve viaduct.