Travel: An oldie hits the tracks: Bearing backpack and notebook, Humphrey Carpenter joined the Inter-Rail trail at the age of 47

I should have done it at 18. Now, at 47, I felt ridiculous. I seemed to be the only person in the P&O ticket queue at Dover who was over 25. All my fellow middle-aged travellers were lining up to get on to the boat in their cars. Here was I with a backpack, trying to blend into the crowd of teenagers filling the months between school and university by freewheeling around Europe by rail. I wished I had a hat to hide my greying hair.

And yet friends of my own age had virtually salivated when I told them I'd bought an Inter-Rail 26-plus ticket, which gave me two weeks' unlimited travel on European trains. In fact, I could spare only a week, while my family were away. Could I get good value out of that ticket between Sunday and Saturday lunchtimes?

Remembering occasions when I had stood on the platform of some European station and gazed longingly at train departure boards announcing exotic destinations, my first inclination was to set off without a plan - to cross to Calais, and then see what French railways could offer. But a glance at the wonderful Thomas Cook European Timetable showed me that Calais was not such a good starting-place as Ostend. From there I could speed off in almost any direction I wanted. And, inevitably, I began to make plans.

An obvious idea was to go east, as far east as possible. My ticket's validity would run out at the old Soviet border, but at least I could get there, and watch them change the train's gauge from narrow to broad, to fit the wider Russian lines (a footnote in the Cook timetable promised this intriguing technical feat). Having previously visited a little of the old East Germany, and Prague, I could now get into Poland, maybe, and Hungary. But going east meant, at some stage, turning round and coming west again, and time was very short. The day before I left, I came up with a solution: a circular trip, mostly on familiar territory, revisiting places where we had spent family holidays. I began to think about (for example) Vienna. For the first time, my wife looked as if she wished she were coming, too.

The two o'clock Sunday afternoon boat from Dover reached Ostend in time for an early supper - a disappointing bouillabaisse in an Edwardian-looking hotel opposite the station. I munched fishbones and reread Graham Greene's Stamboul Train. Would I, too, find melodrama in the wagon-lit?

In fact, I had already opted for a humbler couchette, and had taken the precaution of booking it via my local Thomas Cook. When the 9.34 for Brussels and Berlin rumbled out of platform four, I was unfolding my sparse allowance of blankets, and stowing my backpack in berth 60C. A bottle of plonk bought on the ship soon induced adequate sleep, and I woke in time for a thorough wash- down in one of the cramped loos as we crawled through Potsdam, stopped at Berlin Zoo, crossed the old line of the Wall, and came to rest in Berlin Hauptbahnhof, the biggest station in the old Eastern sector of the city.

Our Berlin family holiday was in the summer of 1991, when euphoria at the collapse of the Wall hadn't yet evaporated, the Trabants were giving way to gleaming Mercedes, and crowds swarmed around Checkpoint Charlie and the Brandenburg Gate, buying bits of 'real Wall' from the Turkish street-hawkers.

Two years on, weaving my way back into the city from the Hauptbahnhof, I found that most of the hawkers and almost all the crowds have gone. Checkpoint Charlie is a building site for something called Das Business Centre. Traffic drives through the Brandenburg Gate as if it were any old archway, not the point at which East and West reunited so dramatically. A rich crank has erected a full-scale replica (scaffolding and painted plastic sheets) of the old Prussian royal palace, halfway up Unter der Linden, but the Bonn government's promise of moving to Berlin and remaking it a sparkling capital is now not expected to be kept in this decade. The shopping streets off the Kurfurstendamm, west Berlin's Oxford Street, display the same arrogant chic as in Cold War days, but the east Berlin suburbs are as drab as ever. In many respects, the Wall still seems to be there.

I was not sorry to move on that night. The couchette conductor was trying to turf an elderly Indian couple off the train because they lacked visas for the Czech Republic, through which we would be passing in the small hours. I reassured him that I had been to Prague last year without a visa. I was allowed to stay on board. The Indians were not. Eastern Europe has not yet let down all its barriers.

It was Tuesday morning, and it was raining in Vienna. Five minutes' walk from the Sudbahnhof, where the train had deposited me, brought me to Klimt's loving couple, kissing inside their golden cloak in the Belvedere picture gallery. I had seen them on our family trip to the city 10 years ago. But we had never visited the composers' graves, so I took a tram to the curiously named Central Cemetery - curious because it's a four-mile ride out of the city - where Schubert, Beethoven and Brahms contemplate a monument to Mozart, in the midst of a true necropolis, a vast city of the distinguished dead.

I had left behind the groups of teenagers who had made me so self-conscious at Dover. They seemed to spend their days sitting in the stations, hunched together for protection, looking anxious. Maybe an oldie with a credit card had an advantage over them after all. I had no one to talk to, but after years of family holidays in which four people had to come to an agreement before doing anything, it was a refreshing change.

But what was a middle-aged writer doing on a trip round Europe by himself? Obviously, he should be writing. I started devising a thriller based on my experiences, and jotted in a notebook, the way writers are expected to.

I was still jotting in the notebook when the next night train deposited me in Venice. That was the week's real shock, to be whisked suddenly into what W H Auden called the bread and wine culture. Mind you, it was raining on the Grand Canal when I took the vaporetto from the station, a stupendous downpour. My notebook got wet. I contemplated the smudged plot-outline and decided that I didn't need a literary task after all. I could simply permit myself to have fun.

My enthusiasm for the thriller resurfaced during the afternoon as I took a boat across the lagoon to Torcello, with its cathedral so ancient that it seems almost pre-Christian. What a chase you could have around those uninhabited islets, with their curious ruins. Yes, I would begin to write that evening. But when evening came, I sat at an open-air trattoria in the Campo San Giacomo dell'Orio, quite unable to pen a word, stunned into a deep passive contentment by the evening sun, the church bells and the sound of someone sweeping leaves.

The French Riviera looked drab by comparison next morning. But I had my first conversation of the week, with a young Australian who, by coincidence, was teaching at Berkhamsted School, where Graham Greene was brought up; he was living in the Greenes' old house. He had spent six weeks on the move, thanks to Inter- Rail, and had had fun but was almost starving for lack of money.

I thought of that guiltily as I ate the plat du jour in the restaurant car of the Cevennol, a few hours later. The Cevennol leaves Marseilles at 12.26 daily and climbs up, via giddy viaducts and tunnels, to the top of the Cevennes, before crawling through the Massif Central towards Paris. I got off at a remote junction straight out of Simenon; but my notebook was packed away now, and I was just drinking in the scenery. A cross-country line took me to Le Puy en Velay, the world capital of lentil cookery, and my first hotel bed of the week. Next morning it was already Friday. Another country train landed me in Lyons, and the TGV high-speed line had bulleted me to Paris by lunchtime.

That night, I made friends. Two Armenians were listening gloomily to zither music in a restaurant on the hill behind the Sorbonne. Several carafes of vodka later, we had pledged undying comradeship. It would have made a good comic scene in the thriller. I had a memorable hangover when I got off the ferry next morning. But I had stopped worrying about my grey hair.

The author is a biographer (his 'Benjamin Britten' was published last year by Faber), children's author and broadcaster, and will be the programme director of the 1994 Cheltenham Festival of Literature.

Frank Barrett writes: Humphrey Carpenter travelled on an Inter-Rail 26-plus ticket (price pounds 209 for 15 days' unlimited travel) assuming it covered all of Europe. In fact, it excludes Belgium, France, Italy, Portugal and Spain. BR International in London says Mr Carpenter was 'very lucky. The guards are normally hot on checking tickets on the Continent. If you are caught without a valid ticket, you must pay the full single fare, and you could be fined. I don't advise anybody to follow his example.' The Inter-Rail 26-plus tickets can be bought from British Rail, Thomas Cook and other agents. Couchettes, which can be booked in advance or at the place of departure, cost about pounds 12 per night.

(Photographs omitted)