There’s a special magic in taking a train from one great European city to another, especially when neither city is in Britain and they are separated by a national frontier. It’s a type of magic that evokes images of an age when international travel involved more than one hour in a pressurised aluminium tube with an airport lounge at each end.

Images, concocted from badly remembered Thirties novels, of writers and artists escaping the dullness of England, of eloping lovers and exiled revolutionaries, of not necessarily brief encounters in poorly lit carriages . . .

With these and similarly bogus thoughts I board the 10.18 Paris-to-Geneva TGV (Train a Grande Vitesse) on a sticky July morning. Four hours earlier I had been watching a Waterloo sunrise from the window of the first Eurostar to Paris. In 15 hours’ time, I will be back in London.

So, I’m not on a Eurorail holiday, nor am I a refugee from airline disputes. I’m just a day-tripper. A London-to-Geneva-and-back sort of day-tripper.

“Are you crazy?” a friend asked me. “You leave home at the crack of dawn, get back after midnight, just for a couple of hours in Switzerland?” And why not? It can be done. Thanks to the Channel Tunnel and Eurostar, we think nothing of going to Paris or Brussels for an afternoon. But why stop there? Europe is criss-crossed by high-speed rail links, and the trains are getting faster. It’s time to redefine our British Rail-bred notions of the day out.

The train seals itself with a barely audible hiss. I am about to be hurled into central Europe by the pride and joy of France’s SNCF rail network, with little to do for the next three and a half hours except watch absurdly beautiful French landscapes unfurl outside my window.

I could read, or attempt conversation. Two young Genevans are arguing with a Parisian couple about racism in France and Switzerland. Before I speak, the skinny, shaven-headed kid from Geneva is explaining to me, in excellent English, the points he is trying to make.

The first cluster of a large bundle of prejudices about the Swiss that I am carrying around with me are quietly jettisoned.

Outside, thickly wooded hills give way to the green mountains of the Jura range. The TGV reverts to normal vitesse as it snakes through valleys, rocks on one side, the Rhone on the other.

At some point we cross the border, but I fail to notice it. Just outside Geneva I see the Swiss flag on a shabby cafe beside a heap of rusting cars. Bang goes another prejudice.

It takes a couple of minutes to run the gauntlet of the French and Swiss customs posts, then out on to the streets, which are a bit cleaner than London’s but not oppressively clean. There is even some graffiti. On the way to my target - the Musee Voltaire, five minutes’ walk from the station - I pass a tiny public garden, in which four men are sharing the local equivalent of a three-litre bottle of Strongbow.

The musee occupies the fine house in which the philosopher lived from 1755 to 1765. For 45 minutes I have the lot - first editions, letters to and from the great man, and incredibly fresh-looking portraits by Jean Hubert - all to myself.

Voltaire eventually left Geneva, angered that its famed tolerance did not stretch to granting political rights to poor refugee artisans. I see several less-than-wealthy-looking artisans on the short walk downhill to the shores of Lake Geneva. I wonder where they live, and consider how poor they are by British standards.

Over the bridge - that little cone in the distance is Mont Blanc - and up into the old town. Below the cathedral in which Calvin dispensed Calvinism to the likes of John Knox, groups of designer-labelled youths are gathering for post-shopping drinks.

Are these the children of Geneva’s super-rich? Maybe, maybe not. This place is quite unlike the City of London, where making money goes with stressed-out people barking into mobiles and knocking you off the pavement. Here, the money has been made, and is growing on its own while its owners relax. I sit and order coffee and a sandwich. It costs a little less than it would in London.

But I can’t relax: the train leaves in 15 minutes. No time to explore the museums, the lake, the huge United Nations complex. What would Voltaire have thought of Geneva’s role as the laid-back host to the world’s war and peace-makers? Back on a train, I jot down various profundities.

Luckily you are being spared these, as the notebook, along with Swiss chocolate, camera, books, and more, fall to an opportunist bag-snatcher at the Gare du Nord. Would this have happened in Geneva? And so new prejudices are formed.

Eurostar. Tel: 0345 30 30 30. Return fare to Geneva Pounds 128 plus TGV supplement of Pounds 5-15