The 11.41am turned out to be pretty full, but I found myself a spare seat next to a teenager playing a car-racing game on his laptop to the accompaniment of blaring Arabic techno. Across the aisle a group of teenage girls in hijabs were writing messages in each other's school books, while a Berber gentleman, completely wrapped in his burnous (a hooded woollen cloak), had his dark glasses trained implacably on me. Either he found me incredibly fascinating, or he'd found me so incredibly unfascinating that one glance in my direction had sent him to sleep.
Overall it was an exotic cross-section of travellers, but then so it should have been. This wasn't the 11.43am from East Croydon to Purley Oaks; it was the Société National des Chemins de Fer Tunisiens day-time train from Tunis to Tozeur, an oasis in the Sahara Desert, although in this instance I was just travelling a short hop down the line.
As its name suggests, the SNCFT owes a fair bit to the French, who created Tunisia's railway network in colonial days, and today a dogged fleet of second-hand trains that first saw service in Normandy or the Auvergne rumble back and forth between the top and the bottom of this small North African country, connecting the vineyards and Mediterranean landscapes of the north with the salt lakes and deserts of the south, and all points between.
It takes the long-distance trains eight hours to complete the Tunis to Tozeur journey, one that is undoubtedly quicker by car. But railways allow you to read, meet people, sleep, and be otherwise entertained, and they trundle their way across the land along uncluttered routes, so that you can easily find yourself gazing into a goat-herder's shelter one minute and passing through strobing rows of olive trees the next. Moreover Tunisia's trains are also pretty cheap: the SNCFT's seven-day carte bleue costs the equivalent of just £15 for a week, giving you carte blanche to go anywhere you like for barely more than £2 a day.
For my train-based exploration I had based myself in Sousse, Tunisia's second city, situated about a third of the way down the country's east coast. Sousse is the Tunisian equivalent of Barcelona: an easy-going place that combines business and culture, plus a port, a promenade and a long, touristy beach. At its core is a 1,000-year-old medina, a walled city protecting a maze of narrow, pedestrian-only streets reeking of charcoal and glue and ringing with the sound of hammer on metal. From the rooftop terrace of the Dar Essid, a restored merchant's house high up in the medina, I could look down on a townscape of tiny coloured pieces like thousands of carefully arranged eggshells, and spy on skinny youths, and skinnier cats, lurking on the street corners of the red light zone.
Tourist shops line the last gasp of the medina where it debouches into the modern town, and a handful of shopkeepers greet the incoming tour groups with typical Del Boy patter. "Come in mate and have a gander," they say, suggesting that their pouffes are all "luvvly jubbly". Meanwhile madrassah-bound students pour down the boulevards outside, watched by tourists sitting on the terrace of the Café Claridge, where a coffee costs the equivalent of 25p. Tunisia is good value if you eat and drink where the locals do.
The beach begins 100 metres on the far side of the café, and here the Muslim world gazes curiously at the Europeans in bikinis, these tourists careful to get every last ray of the winter sun. Some of them are guests at the just-opened Movenpick Resort and Marine Spa, whose choice of Sousse for Tunisia's largest five-star property is a feather in the city's cap.
The railway station is wedged between this coming together of cultures, between the traditional medina and the hotel-lined beach, and walking distance from both. When I last travelled this way, the trains ran right through the heart of the city, bisecting the fishmarket and the busy main square; the diesel cussing at taxis and pedestrians, and train passengers eyeballing the bus drivers. This time a fence separated the square from the station, and the trains prowled around behind it, grunting like caged animals in the zoo. Apparently too many people had been killed on that rumble through the throng.
For the first journey of my trip, among those teenagers on that day-time train, I travelled an hour south before clambering off at El Jem to see the massive Roman amphitheatre – which makes even more impact than Rome's Colosseum thanks to the way it rises like Uluru out of a scruffy low-slung town. And this wasn't the only ancient history that I discovered was visitable by train; the next day I took the express the other way, for the 90-minute journey up to Tunis and then on the local connection to Carthage Hannibal station, emerging amongst the charismatic rubble of Carthage itself, amongst 2,500-year-old bathhouses and temples.
The most interesting journey was the night train south, towards the Sahara. The majority of the passengers were elderly, and I found myself in conversation with a tall, gangly, crackling Mauritanian with a wallet full of old travel tickets, which he was unaccountably keen to show me. "C'est cher, c'est cher," he repeated, waving each one under my nose. He left the train in the middle of the night, but insisted on waking me for fond goodbyes.
We arrived at Metlaoui shortly after 6am, when the sky was beginning to glower with the first angry warnings of dawn. The town turned out to be sprawling, mud-walled, and filled with shadowy cloaked figures looking like something out of Star Wars – which was filmed nearby. Yet its railway yard was abnormally large thanks to a prospering phosphate mining industry up in the Saharan Atlas. Those arid mountains were the reason I'd come here; they featured as the location for the agonised cave scenes in The English Patient – and they also host a rather special train, the Lezard Rouge, which crawls up through river-gouged canyons in one of the world's most starkly scenic rail journeys.
The Lezard is a sort of Arab Orient Express, and was given to the Bey of Tunis by the French in 1952, at the time when France was seeking permanent rights to Tunisian land. It wasn't a productive gesture. The Bey, who only used the train to pootle down to the shops, was soon swept aside in Tunisia's rush for democracy. These days it is privately owned, walnut-walled, mirrored and with leather sofas and armchairs, and every day it carries tourists from Metlaoui up into the foothills of the Atlas mountains.
Initially it skirts the mountains, but then dives in, threading up slowly through rock-cut tunnels, flickering in and out of the sunlight, broaching secret valleys, crossing and recrossing a rivulet of mud which turns into a canyon-carving torrent on the rare occasions it rains. It stops a couple of times in particularly otherworldly cliffscapes, and everyone piles out. After an hour it reaches the top, a shunting yard next to the phosphate mine, and then you trundle back down, through deep romantic chasms and caverns measureless to man, to Metlaoui again.
This was where my train odyssey ended, too, even though I hadn't quite gone all the way to Tozeur as intended. In this arid zone there were only two trains a day, and I would have had to wait several hours for the next one. So, in the end, my return journey to Sousse was not as ideologically correct as it should have been, but in a shared taxi with the music turned up loud by a driver who trusted in Allah and let the highway code look after itself. Sometimes one has to sacrifice one's nerves for the sake of convenience.
'Blue River, Black Sea' by Andrew Eames is published by Black Swan (£8.99)
* The writer travelled to Tunisia with Tunisair (020-7437 6236; tunisair.com ), which flies from Heathrow to Tunis, and Tunisia First (01276 600 100; tunisiafirst.co.uk ), which offers a range of holidays to Tunisia. Tunis is also served by BA (0844 493 0787; ba.com) from Gatwick.
* For train timetables and carte bleue rail pass details, visit sncft.com.tn .
* The Lezard Rouge (00 216 76 241 469; lezard-rouge.com ) departs Metlaoui Sundays-Fridays at 10.30am (10am Tuesdays and Thursdays) and costs 20 dirhams (£9.20).
* Tourist office: 020-7224 5561; cometotunisia.co.ukReuse content