The 8.55 to Baghdad by Andrew Eames

In 1928, Agatha Christie set out on a whim on what seems, today, a highly unlikely journey, but one which was to completely change her life. It was an eight-day trip from London to Baghdad by two aristocratic luxury trains, with black tie waiters all the way. It was also the key to what she herself described as her 'Second Spring', because in the desert she met a young archaeologist whom she later married. For the next 30 years, she would spend every winter season in the empty wastes of Syria and Iraq, piecing together pottery and handing out laxatives to sheikh's wives.

In the last days of peace before the Iraqi war, I set out to re-trace this little known adventure in the life of Britain's best-selling author. I quickly realised that London to Baghdad, by train, is one of those journeys which has defied the modern era by becoming far harder, and longer, than it was 75 years ago. My motley selection of eight ramshackle sleepers and local expresses took two days more than Agatha's Wagon-Lits, and from Venice onwards there was no glimpse of a folded napkin, let alone a glass of chilled Bordeaux. The ultimate indignity was the mandatory AIDS test on the Iraqi border.

Agatha's journey came at a crucial moment in her life. At the time, she was a 38-year-old mother of one and already successful. But, she'd just gone through a traumatic divorce from Archie Christie, during which she'd mysteriously disappeared for 10 days. She was discovered staying in a hotel in Harrogate under an assumed name having apparently lost her memory.

Once the divorce was settled, she decided she needed a holiday, canceling initial plans to go to the Caribbean after meeting a couple who'd just come back from Iraq. Quite a destination change, you might say, but at the time Iraq was British-controlled Mesopotamia, and archaeological discoveries at the ancient city of Ur were the talk of the town. Besides, Thomas Cook had just started to offer a London-Baghdad package thanks to a combination of the Orient Express to Istanbul and the Taurus Express to Damascus. And, Agatha loved trains.

In truth, it is hard not to love the Orient Express, which still runs today very much as it did in her time, right down to the coal-fired water heaters and the Lalique glass panels in the dining cars. The current train owners have been remarkably faithful to every detail, and I departed Victoria at exactly the same time as Agatha would have done, in a coach which was built a year before she made the journey and could easily have been part of her train.

Despite its vintage, the Orient Express was my fastest train of the whole journey, covering 1,071 miles in 31 hours. When I disembarked at Venice I still had 1,500 miles to go, which would take a further eight days. But while the Orient Express had a price tag of £1,310 one way, those next 1,500 miles would cost me just £72.03.

Agatha's fare, however, was a whopping £87 - the equivalent of £3,831 today - so the journey may have got longer, but it has also got cheaper.

In those days the Orient Express went all the way to Istanbul twice a week, carrying spies, aristocrats and government officials; these days it makes the full trip only once a year, so I had to enter the Balkans on the Drava, a manky old train quarter-filled with labourers staring at their boots.

In Slovenia, I made a detour to Lake Bohinj, where Agatha and second husband Max had once tried to holiday incognito, only to be run to ground by enthusiastic Slovene journalists. There I met Janez Cucek, the cub reporter who'd got the scoop interview by booking the room next to theirs and then climbing across the outside balconies like the man from Milk Tray.

From there, it was onto the Croatian capital Zagreb, a city with one of the ugliest names on the planet. Although Agatha had rattled through in 1928, I stopped to look at the Esplanade, a grand hotel built specifically for Orient Express customers, and the only relic of that glorious era of travel that hasn't been swept away by communism.

From Belgrade, a ropey sleeper delivered me to the Bulgarian capital, Sofia, and from there I took another sleeper to Istanbul, where Agatha had disembarked from the Orient Express. Here the Pera Palas, also built for Orient Express customers, had a menu that featured macaroni cheese, and was more of a museum-piece than a hotel. The room that Agatha habitually reserved was by no means the best in the house - those were the suites once occupied by the likes of Mata Hari and Albania's King Zog - but it did have an authentic-looking writing desk and a cabinet of her books.

Back in 1928, the author had spent a couple of days here before crossing the Bosphorus to Hydarapasa, the railway station for all points east. From there the Taurus Express, a sister train similar in style to the Orient Express, departed for Syria.

I, too, crossed the Bosphorus on an aged ferry to catch the Toros Ekspresi, although these days the latter is a trans-Turkey train full of chain-smoking factory workers. Recent improvement in cross-border relationships meant that it does, however, also have a once-weekly Syrian sleeper car attached, supposedly to go all the way through to Damascus.

After 30 hours of travel, this sleeper was finally amputated from the Turkish train to trundle through empty mountains at the head of a string of rusty trucks, waiting for hours at the frontier stations as our corridors were filled with cardboard boxes of illicit merchandise. How things had changed since Agatha's day!

On the Syrian side of the border, the contingent of seven passengers was reduced to five when two were found not to have the right paperwork. It was an average load, said Bedur, the kurdish train driver sent up from Aleppo to collect us. Recently they'd received a sleeper which they'd all assumed was empty, and had left it locked in a siding until the lone passenger, a Turk, had summoned help via his mobile phone.

By now our 'express' was eight hours late, and my fellow passengers abandoned ship in Aleppo to continue to Damascus by bus. I, however, made a beeline for the Baron Hotel, the run-down colonial watering hole where Agatha and her second husband had frequently stayed. Like the Pera Palas, the Baron has yet to have a makeover from a multinational, and it is still owned by the family who built it, with whom Agatha and Max had become good friends. Agatha's room was occupied, but I was able to stay in the room next door.

I had less luck with the Orient Palace hotel in Damascus, also built for luxury train travellers, but now filled to the rafters with muslim pilgrims. This is where the train element of Agatha's journey ended - the Baghdad railway was yet to be completed - and where she put herself in the hands of the Nairns, two fearless New Zealanders who ran what was effectively a limousine service across 500 miles of featureless desert.

For my desert crossing I joined an unlikely bus-load of supposed tourists, led by a man who had good contacts with the Iraqi regime. The ostensible focus of our visit was archaeology, as it had been for Agatha, but we were arriving at the same time as the last of the UN weapons inspectors. Accordingly several members of the party had clandestine motives; two were journalists, two were surreptitiously making a TV documentary with camcorders, and one was presumably the man from the ministry. We all had our AIDS test at the border, with syringes we'd all taken care to bring in our hand luggage. The tester never even bothered to label the samples: it was the $50 fee that counted, not the results.

In Baghdad at last, the Iraqis in the street seemed delighted to see foreigners. Agatha, too, had been impressed by their hospitality. In her second life she and Max had had a house here, on the banks of the Tigris, and her publishers would fly out copies of the Times. Sadly the house is no longer, but the railway station she used on subsequent journeys still stands, so I determined to make it a final point of my pilgrimage to mark the completion of my adventure emulating hers.

But first I had to give my minders the slip, because the terminus, built by the British and looking like a cross between a mosque and Battersea Power Station, was off-limits to foreigners. The Iraqis were supposedly moving their armaments around by train, so by stepping out onto platform one I was effectively labelling myself a spy.

Of course the inevitable happened. Soldiers materialised out of the shadows, and I was frog-marched into the guardroom. There I had a bizarre conversation with a smiling man in a white shirt, in which we established that I had two children while he had eleven, that I came from a country where it rained all day, and that I was completely and utterly a tourist. Yes sir.

Somehow my inadequacy in the fathering department, combined with the awfulness of my weather, earned me the sympathy vote. I could look at the station, said the secret police chief, but I must not take photos.

Repeating 'no photo', and bowing repeatedly like a Japanese tourist, I backed out of the guardroom. I took a cursory look around the empty booking hall, and fled.

I had finally reached Baghdad station, 75 years after Agatha, and it had nearly given me a heart attack.