With the summer holidays here, many of us will be planning a getaway – but with air fares rising in line with sea levels, there’s much to be said for enjoying what’s on your doorstep rather than jetting to foreign climes. And there are few better ways to do that than taking the West Highland Line to Mallaig, whizzing past extraordinary vistas of lochs, mountains and nuclear facilities at speeds approaching 25mph. So may I present my officially unofficial, intermittently accurate guide to one of the greatest rail journeys in the world.

Built in 1901 to take herring to London, in an era when fish had much higher disposable incomes than they have today, the line today is geared more towards human tourists. On departure from Glasgow, the spectacular algal blooms of the Clyde only begin to hint at the further wonders that lie ahead. The train continues through Helensburgh and Garelochhead – handy for stopping off at the Faslane naval base, where the excellent gift shop sells fully functional scale replicas of its nuclear submarines, guaranteed to liven up any bathtime.

The next station, Arrochar and Tarbet, lies on a narrow isthmus between two lochs. During the Scottish-Norwegian War of the 13th century, Viking invaders would haul their longboats across this stretch of land to continue their passage. Warriors who completed this arduous task were rewarded with extra pay and rations, known as an Isthmus Bonus. The train then proceeds north past Loch Lomond which, despite its proximity to Glasgow, remains an oasis of serenity, punctuated only by a few hundred passing speedboats, jet skis, cruise ships and supertankers.

Crianlarich, best known for once having had a Little Chef, is where the Mallaig and Oban lines meet, which means a wait of around ten minutes while the train divides. As a result, the station has long been beloved of smokers, who gather on the platform and attempt to consume as many cigarettes as physically possible before the scheduled departure. The all-time record is held by the late Willie ‘One Lung’ Jackson of Lochailort, who on 23 October 2004 managed 13 roll-ups and a cheroot before being ushered back to the train. Nowadays, smoking is officially prohibited even on the open platform. Much like the rule outlawing on-train alcohol consumption, this is both warmly endorsed and religiously observed by regular users of the line.

In the wilderness of Rannoch Moor, there are no roads for miles around, and the surrounding moorland is wet and treacherous, illustrated by the many abandoned, half-submerged rail replacement buses visible from the train window. Corrour station is the location of the ‘Great Outdoors’ scene in Trainspotting, in which Renton and friends get off the train and decline to climb a mountain. Rumours that the same train also inspired the film’s ‘Worst Toilet in Scotland’ scene remain unconfirmed.

The train continues north to Tulloch, where it dawned on the railway’s engineers that they’d missed Fort William by about 15 miles, so the line takes a sharp left and proceeds southwest. It passes the Commando Memorial, which honours a local regiment who helped conserve scarce textile resources during World War II by going into battle without underwear. Their sacrifice became a symbol for British stoicism and led to the coining of the term ‘crack troops’. Approaching Fort William, the twin landmarks of McDonald’s and Ben Nevis come into view, and no trip to the area is complete without visiting at least one of them.

As the train crosses the Glenfinnan Viaduct, it slows to allow passengers to admire the glorious view over Loch Shiel, which is of minimal interest to the thousands of grown men and women who visit each year solely to follow in the footsteps of a fictional schoolboy wizard.

On the station platform, local entrepreneurs flock to sell Harry Potter-themed postcards, keyrings and gimp masks to enthusiastic tourists – whose children, meanwhile, remain on the train, valiantly trying to get TikTok to work with one bar of mobile signal. They have no idea who Harry Potter is.

At Arisaig, the line affords stunning views of the islands of Rum and Eigg, named after the two most popular breakfast items in the West Highlands, before the train reaches its final destination of Mallaig.

The once mighty fishing industry here has declined from its 1960s heyday, but the sea continues to play a vital part in the village’s economy, and species as diverse as prawns, haddock, salmon and mackerel can be found in the Mallaig Co-Op to this day.