The Man Who Pay His Way: The cost of the Eurostar train in Spain falls way below the plane

Hola, compañero. Pour me una cerveza and slice the chorizo before I take my siesta: this week I have moved to Spain... Actually, that is not strictly true. What I have done this week is pretend to live in Spain. The idea is to save money – not by evading tax, but by circumventing the ludicrous fare rules on trains that go through the Channel Tunnel.

I described last month how my sister had booked an unwanted two-night stay in a hotel in Brussels, in order to save £175 on Eurostar tickets from London via the Belgian capital to Amsterdam. This loophole exists because hotel-inclusive packages with Eurostar have a special allocation of seats at fares that can sharply undercut tickets sold without accommodation.

Misrepresentation to the Channel Tunnel train operator is fast becoming a family trait, because this week I told Eurostar a small but profitable mentirilla (fib) about where I reside.

The walk from my home to the Eurostar HQ at Waterloo station takes 10 minutes. But by claiming residency en España rather than in SE1, I have saved an astonishing 82 per cent on the price of a ticket from London to Paris. To put it another way: British travellers are being charged punitive fares, more than five times as high as Spanish people for an identical journey.

Exhibit A, which I have just been on a 10-minute walk to collect, is the cheapest available one-way rail ticket from London to Paris – if you have the misfortune to live in Britain. The fare for the journey, on 4 December, is £154.50. The trip will start on the new high-speed line from St Pancras, which opens on 14 November. The fare works out at £1.15 for each minute. Exhibit B, which I picked up on the same trip after donning a sombrero and comedy moustache, is the cheapest available one-way ticket from London to Paris on the same day – if you have the good fortune to live in Spain. The fare is just €38.50, which works out at a very reasonable £27.50 or only 20p a minute.

The tickets are for identical journeys in standard class. The vastly more expensive ticket has a couple of additional benefits: the journey may be changed without penalty, and is fully refundable (just as well, because I need only one ticket for the trip). To get the cheaper ticket you may need to book and/or travel off-peak, though booking six weeks ahead from my residence in "Spain", availability was wide open on the whole day's trains.

The first rule of air travel used to be the certainty that the person in the next seat had paid less than you. Now, the first rule of travel on the UK's only high-speed rail line is: if the person next to you has the sense to be Spanish, he or she will have paid one-fifth of the British fare. For evidence of "rip-off Britain", you need look no further than Eurostar.

Legally, I could end up in agua caliente. By pretending to live in Spain, I have sought and procured pecuniary advantage by deception. This looks suspiciously like a possible offence under the 1968 Theft Act.

I confessed my misrepresentation to Eurostar, and the company does not intend to press charges on this occasion.

But why should cheap rail tickets be the preserve of travellers living in Spain, or at least those pretending to do so?

I asked Eurostar to explain the commercial, legal and moral case for making us pay more than five times as much as the Spanish.

"It's not something we set out to do deliberately," says Eurostar's Gareth Headon. "It's an unintentional quirk."

While airlines have long used universal reservations systems, railway ticket sales are living in an earlier century. Eurostar trains are distributed through no fewer than 48 individual sales systems. The one that applies to Spanish travellers is markedly different from those in the UK, France and Belgium. "It gives customers the possibility to split the cheapest return journey and selling just one half," says Mr Headon. He adds, ominously, that the company is looking to close the loophole.

IN A properly competitive environment, Eurostar would long ago have fallen into line with the now-standard practice of fair fares with no penalties for one-way or short-duration travel. But since 14 November 1994, when the Channel Tunnel opened, the air-travel market from London to both Paris and Brussels has steadily shrunk, to the considerable benefit of Eurostar and to the detriment of competition.

In the early Nineties, London-Paris was the busiest international air route in the world. Travellers could choose from around 50 flights each day, each way, with services from all five of the UK capital's airports. Links from Gatwick and Stansted have ceased, and BMI has abandoned the route between Heathrow and Charles de Gaulle.

After the acceleration of Eurostar from next month, Air France will cut at least four of its daily dozen flights between the two airports. British Airways says it has no plans to reduce its 10 daily flights on the route. But with slots at such a premium, and more passengers likely to switch from air to rail, further cuts seem unavoidable.

It's good for the environment; but if Eurostar behaves much more like a monopoly provider, the traveller will be the loser.

Arrow to San Sebastian

Never mind living in Spain; for the first couple of decades of my life, I didn't go near the country. The reason was a family-wide boycott of the country ruled by the fascist dictator, General Franco. Since I first hitch-hiked south to the Basque Country in 1977, after he had died, I have been trying to make up for lost time. And the closer you get to November, the more alluring life in Spain appears.

By tapas time on Monday, I should be in San Sebastian, the city that first seduced me. Since no airline flies from the UK direct to the city's airport, and the train journey takes at least 11 hours, I shall fly out from Stansted to Biarritz on Ryanair and back from Bilbao on easyJet.

Gatwick-San Sebastian looks an obvious link for a carrier such as Monarch or GB Airways. It would cover a distinct catchment area at both ends of the route, and appeal to a relatively wealthy market which would pay for more than the basics.

Tim Jeans, king pin at Monarch, says the absence of a direct service " is down to slot availability at Gatwick. There are simply no opportunities to grow."

If GB Airways were to take up the route, moving to Spain would appear even more tempting – because owning property can save you cash on air fares, too. The airline has launched an affinity scheme for overseas homeowners. " GB Privilege" offers guaranteed access to the lowest fares, and advance notice of seat sales. You can register at gbairways.com/gbprivilege. Be sure to tell the truth about where you live.