SCOTRAIL attracted global media attention last week when it advertised for drivers for the West Highland Line. Why? Put simply, because the line is the greatest railway journey in the world, one that you must ride on at least once in your life.

I spent more than a decade as contributing editor of International Railway Traveler in the US and I’ve been lucky to ride most of what are hailed the world’s great railway journeys. Yes, the Trans-Siberian and the Orient Express were both remarkable experiences, as was rattling coast-to-coast across both Australia and the US.

But hand on tartan heart there is really nothing better than the line, which runs from Glasgow Queen Street to Mallaig. Purists may argue it technically starts at Craigendoran Junction, but I recommend terminus to terminus.

The West Highland Line was built to serve the tourism and fishing industries. Originally the route only went as far as the old garrison town of Fort William, which it reached in 1894. It was not until 1901 that it finally made it to Mallaig.

Near Helensburgh, at that Craigendoran Junction, the West Highland Line splits with the mainline and starts to ascend. The Clyde is soon replaced by Loch Long, Loch Goil and Gare Loch as the diesel train struggles with the steep climbs.

The line soon flirts with Loch Lomond, with glimpses of the island-studded waters sneaking between the forested slopes. As we push on to Crianlarich, we soar more than 500 feet in five miles, a testament to the engineers who forged the line.

At Crianlarich the train splits, with some carriages breaking west towards Oban. After the separation the remaining two carriages edge further north as the views just get better and better.

One of the most dramatic set-pieces of the West Highland Line is the Horseshoe Viaduct, a sweeping curve and viaduct that were only built as a cash-saving measure.

It would have been quicker to cross the glen in one go, but financial limitations meant this glorious loop took shape between the solid masses of Beinn Odhar and Beinn Dorain.

In contrast to the winding track and steep gradients of much of the route, Rannoch Moor is a plateau we roll across with seemingly little effort. This illusion belies the difficulty of laying a track across the sodden, inhospitable moor that Robert Louis Stevenson so dramatically immortalised in his novel Kidnapped.

Initial attempts were disastrous as the bog swallowed up all spoil laid on it. The eventual solution was to “float” the track across. Rannoch Station itself stands in splendid isolation, a tiny dot miles from the nearest human settlement. Soon after Rannoch, the West Highland Line reaches its highest point sliding into Corrour, at 1340ft the UK’s highest railway station.

This is the station where the protagonists from Irvine Welsh’s Trainspotting decamped for some Highland walking, but were quickly deterred by Leum Uilleim’s imposing slopes.

Ben Nevis looms over the arrival into Fort William. Then the train hugs the shores of Loch Linnhe, the first sea loch. The track struggles through the demanding terrain of the West Highland Line Extension, a 39-mile major feat of railway engineering, necessitating a mass of rock cutting and drilling, the building of 11 tunnels and five major viaducts.

Much of the credit for its success – it was finished a year ahead of schedule – went to Robert McAlpine, or “Concrete Bob” as he became known, due to his innovative use of the material. In summer the Jacobite steam train runs on the extension line between Fort William and Mallaig and vice versa, serving up swathes of nostalgia. While more casual tourists admire the view, real rail lovers crane their necks out of windows to snap photos of the steam engine pummelling its way seawards.

The most scenic section – arguably the UK’s greatest rail vista – is at Glenfinnan, the viaduct so loved by Harry Potter fans. The train squeals around the 21 arches, one of the finest examples of engineering from the golden age of the railways. Initial objections that the viaduct would spoil the glen’s beauty quickly dissolved when it became obvious the viaduct only enhanced the dramatic scene.

One anecdote recalls that horses who tumbled to their deaths inside the viaduct’s pillars during construction were buried there.

The landscape now opens up with glimpses of the Small Isles of Rum, Eigg and Muck, which hang tantalisingly offshore, and tease in and out of view on the run to Mallaig.

This part of the line includes the Leachabhuidh Tunnels, the Glen Mama Viaduct and the impressive Borrodale Viaduct, as the train slides through rock cuttings, squirms around hillsides and negotiates the sea loch punctuated landscape.

In a final scenic flourish before Mallaig the white sands around Morar and Arisaig twinkle into view against the clear blue waters. Morar is another handy stopping-off point, boasting impressive beaches that are ideal for sunbathing in summer, or bracing strolls in the colder months, as well as one of Scotland’s shortest rivers, the Morar. There’s Loch Morar too, Scotland’s deepest loch.

At Mallaig the West Highland Line rallies to its end with the squawk of seagulls and the sweet tang of salty sea air. It feels a million miles away from the industrial landscape of the Clyde – and it is. And what a journey it has been, in every way.

No wonder the job adverts created a media storm.