A white beam lit up the wall above my head and I gathered the faux-fur covers around my shoulders and edged towards the window. It was cold in my compartment and the air held the sour dankness of the guards’ cheap cigarettes. Lifting a corner of the curtain, I squinted outside.

Disorientated, I touched my forehead to the glass and then I saw them, smiling. Above the clocks found on the front and back of each of the country’s railway stations, hung the illuminated, framed round faces of Kim Il Sung and Kim Jong Il, a paternal picture of jollity. It was three o’clock in the morning. Then I remembered where I was: on a train in North Korea, travelling overnight from Chongjin to the port city of Wonsan.

Crawling back into bed I took out my iPhone and began to watch a video I had filmed that morning at the Steelworks Kindergarten in Chongjin. More than 25 children aged from three to seven years old had put on a performance for our tour group so precisely styled and executed it would have put the Bolshoi Ballet to shame.

The train eased away from the station as I flicked through photographs of their playground which had featured a slide, a rocket, a tank, and a submarine with a torpedo on the side. Unable to sleep, I made some notes by the light of my phone, then panicked and tried to scratch them out in case anyone chose to read them. Realising I was being ridiculous, I gave up as the train began to sway in the darkness, and dozed off under the mustiness of the covers.

When I began my train travels around the world for my book Around the World in 80 Trains, I wrestled with the concept of visiting North Korea. Like the majority of travellers, I was unaware that the country has been open to tourists since 1953, although until 1988 it was restricted to visitors from ‘friendly’ and non-aligned countries. Currently more than 5,000 Western tourists visit North Korea each year, with sanctions and sporadic nuclear testing doing little to dissuade them.

Only in mid-March an American student was detained in Pyongyang and sentenced to 15 years hard labour which did not deter the 1,000 foreign tourists who took part in the Pyongyang marathon less than three weeks later. Just this week, a BBC team was expelled from the North Korean capital for “speaking very ill of the system”, and I was acutely aware of the choreographed show that the country presents to tourists.

But my reason for visiting was simple: I was curious. I don’t believe everything I read, see or hear, preferring experience to prejudgment. So when I discovered that the British-owned, Beijing-based Koryo Tours runs an annual 10-day train excursion, extending beyond the showcase capital of Pyongyang – and that it coincided with the 70th anniversary of the Workers’ Party – I booked my place on board, amused that it cost the same as one night on the Venice Simplon-Orient-Express.

The tour began in Pyongyang and would take us to Wonsan, Hamhung and Chongjin before finishing back in Pyongyang. Curious about the kind of people who would want to visit North Korea, I was pleasantly surprised by the motley crew of 14 with whom I was travelling, which included a Canadian on his fourth visit, an American Cold War veteran, an IT consultant from Cheltenham and a couple on honeymoon.

Unable to travel on public transport without close supervision, we were provided with a chartered train comprising Swiss carriages from the 1970s with comfy seats and enormous pull-down windows. It was a far cry from the rusting old Chinese trains reserved for North Koreans only.

From the outset it was made clear that this was the Democratic People’s Republic of Korea, or the DPRK – definitely not North Korea, as the Koreans prefer not to recognise the existence of their southern counterpart. On the first morning we arrived at Pyongyang station just as the clock marked the hour and a tune crackled from loudspeakers in a haunting minor key, like the soundtrack to a sci-fi movie.

The station looked like a concrete airport hangar, and was empty but for our train and our guards waiting on the platform. No ticket machines, no passengers, no trains, no whistles, no announcements. Just us.

Once our bags were stacked and we’d run around and checked out the sleeper berths, fingered the blankets, peered at the toilet, and forced down the windows, we were on the move and began to glide out of the city, past the anomalous, rocket-shaped Ryugyong Hotel gleaming in the sunshine.

Within minutes we were racing through the countryside, fields ablaze with corn, the odd cyclist carrying a stack. A circle of jets in formation passed overhead, practising for the upcoming anniversary celebrations, and everyone had taken up spots at the windows, cameras in hand, absorbing the shiny newness of it all.

It was refreshing not to be in the constrained confines of Pyongyang, but in a more natural environment watching people go about their daily routine unhindered. However, the narrative is never as linear as it seems. It helped that we were travelling with Geoffrey Cain, a former journalist and author, now studying for a doctorate in Korean Studies.

Cain explained how North Korean towns and villages operate on a tiered system – if you’re from a politically favoured family, you get the privilege of living in Pyongyang, whereas those lower down the scale must live elsewhere. The privileged also receive access to better education and infrastructure – which includes railway lines. So even though the towns we passed seemed lovely, the houses sturdy and the people even more so, these areas were significantly more prosperous than others.