This year marks the centenary of Britain’s top mechanical celebrity: the Flying Scotsman locomotive. It emerged from the Doncaster works of the London & North Eastern Railway (LNER) in 1923 and is celebrating its anniversary with an exhibition at the National Railway Museum in York, special excursions and visits to heritage railways around the country.

Scotsman is often described as an icon, but what exactly does it represent? I would say early British PR. There were Flying Scotsman ashtrays, jigsaws and paperweights – and the loco often hauled the train of nearly the same name, the Flying Scotsman (train names being preceded by the definite article), which was glamourised by the LNER, with its onboard barber, cinema carriage and Louis XIV-style restaurant car. But why all the glitz?

The LNER, like most showoffs, was insecure. The main transport trend during the interwar heyday of the Flying Scotsman was the rise of the internal combustion engine. For the first time, trains were not necessarily top dog in the transport world, hence the paranoid slogan that began to appear on LNER posters: “It’s Quicker By Rail”. As Bob Gwynne, author of a book on the loco, puts it: “The Scotsman campaign was partly meant to lend a warm glow to the railways in general.”

In that sense, the Flying Scotsman was an anti-car icon, which gives it in retrospect environmental credibility. And while most of its centenary events are sold out, you can see evidence of the railways’ historical battle against the roads on any visit to Britain’s heritage railways.

North Yorkshire Moors Railway

The NYMR is – like many heritage railways – a line restored by volunteers after being closed by Dr Richard Beeching in the 1960s. Beeching was installed as British Railways chairman by the Conservative transport minister Ernest “Ernie” Marples – a veritable Dick Dastardly, if you’re a rail fan. Marples drove a Jag and founded a company that built roads. He encouraged Beeching (a physicist) to take a “scientific” approach to Britain’s railways, which turned out to mean slashing the network by a third without regard for the utility of a line, or indeed its beauty – and the one through the wild North York Moors from Whitby to Pickering was particularly beautiful.

Eighteen miles of it – from Grosmont to Pickering – were reopened in 1966, and the NYMR runs some luxurious teak carriages hauled by the old LNER expresses, including one that featured on The Flying Scotsman train. These carriages, with their art deco mirrors and plush seats, were boudoir-like to seduce wealthy business travellers away from the new trunk roads. Their mellow, tawny interiors are complemented by the russet shades of the hillside bracken in winter or a moorland sunset at any time of year.

The NYMR runs specially adapted steam trains from Grosmont to the gracious, waterfront station at Whitby, which is on the national network.

Strathspey Railway

Aviemore’s pretty chalet-like station is on the Highland main line. But there’s a very prominent petrol station nearby, and on a sunny day the town, with its low-rise architecture and wide car parks under big skies, has something of an LA feel about it – a reminder that the Highlands are a magnet for motorists. Since 1978, the Strathspey Railway – which revives a stretch of the old Perth-Inverness (via Aviemore) line closed by Beeching – has been a corrective to that.

The line runs through the Cairngorms national park, and the SR website states: “We are delighted to welcome customers with bicycles or dogs.” When I was last on platform 3 of Aviemore station, where the SR is based, there were plenty of both, sometimes with a fishing rod thrown in. As our journey began, the adjacent fields and woods of birch or pine were sun-dappled, but a purplish haze over the Cairngorms to the west indicated heavy rain. “Oh,” said the train guard, “there’s usually about five types of weather going on there at once.”

Swanage Railway

Beeching had it in for lines to seaside resorts, whose ridership was minimal in the off season. The pretty line to Swanage in Dorset via Corfe Castle appeared to have dodged his axe, but it closed in 1972. It reopened in stages from 1979, the volunteers having to fight off a road expansion scheme.

Victorian Swanage was “made” by the railway, and the alliance has been restored. You can’t see the sea from the station but you can hear it when it’s rough, and when it’s calm the genteel station announcements are audible from much of the town. In BR Southern Region green, the station is redolent of that 1950s seaside innocence that Beeching assailed. It displays vintage posters featuring bathing beauties with permed hair and slogans aimed at the automotive enemy: “Arrive Earlier by Train”.

Some SR services connect to Wareham on the national network.

Ecclesbourne Valley Railway

The Ecclesbourne Valley line in Derbyshire closed to passengers in 1947, but the track was used to test diesel multiple units, seen as key to the cheap operation of country branches being menaced by cars. Today, the star attraction of the EVR (reopened in 2002) is a single unit from the first generation of those early diesels – the Derby Lightweights, which are as endearing as their name suggests.

The unit is dark green, with straw-coloured “speed whiskers” painted on the front – a kind of go-faster stripe that actually suggests the moustache of a dandified old man. The seat coverings are a lovely, paler green, and all this verdancy harmonises restfully with the gently rolling hillsides and the small but dignified Victorian stations.

The EVR shares Duffield station with the somewhat brasher units of the Midland main line.

Kent and East Sussex Railway

This line opened in 1900, serving farms. It closed in 1961 and was revived from 1974.

It was a “Colonel Stephens railway”, meaning it was part of the empire of country lines built on the cheap by the maverick Colonel Holman Fred Stephens. A typical Stephens line was not fenced off but would just wander through a field. A station might be nothing more than an old carriage; signals were usually dispensed with.

At its Tenterden terminus (accessible by bus from Ashford or Headcorn mainline stations), the K&ES has a fascinating museum dedicated to the colonel. There’s a waxwork of him sitting at his desk – a hawklike, formidably moustachioed man. He looked like a cad, but he fought the good fight – against the car. Posters around the K&ES carry his peremptory slogans: “Travel in safety across the country, away from the dusty and crowded roads”, or simply: “Travel back in time”. You can do just that on the trains of the K&ES, which are no more disruptive of the sleepy Kentish Weald than the adjacent River Rother.

Romney, Hythe and Dymchurch Railway

As mentioned, most of the Scotsman centenary events are sold out – but if you travel to the RH&D in Kent (accessible by bus from Folkestone, Ashford or Canterbury), you can see some 1920s locos modelled after Scotsman, but one-third the size. One is called Green Goddess, another Southern Maid. You might see their drivers polishing their boilers prior to setting off from Hythe, running behind sea-facing bungalows towards the great grey beach (and nuclear power stations) at Dungeness – a setting that makes this 15-inch gauge line even more dreamlike.

The question of whether it is a heritage railway is moot, since it has been operating more or less continuously since 1927 and it’s not just a pleasure line. Local people can buy shares in the railway, thus getting discounted travel for car-free shopping in Hythe. So even though it was founded by a motor racing enthusiast, Captain Jack Howey, the RH&D fights the good fight.

• Andrew Martin is the author of Steam Trains Today (Profile, £9.99).