President Clinton doesn't want you to go on holiday. OK: that's an exaggeration. What the world's most powerful man wants to stop you doing is going on holiday to Cuba.

There are two main reasons why you might decide to book a trip to Cuba. The first is the opportunity to visit the last sensible bastion of socialism, a nation that has survived for nearly 40 years under the guidance (or should that be "thumb"?) of Fidel Castro, the world's longest-serving political leader. The second is that the Caribbean's largest island has some splendid beaches and decent rum, and happens to be stupidly cheap at the moment. But whichever reason applies, Mr Clinton has placed all sorts of obstacles between you and Havana.

Britain's travellers are caught up in the economic war being waged by the United States against what it says is an oppressive and undemocratic regime. There are, of course, many oppressive and undemocratic regimes in the world, but the only one that Washington makes a fuss about us visiting is Cuba.

You might imagine that the British should be able to travel without outside interference. But the tentacles of Mr Clinton's economic embargo extend so deep that Britain's biggest tour operator, Thomson, has withdrawn its holidays in Cuba for fear that its directors would be denied permission to travel to the US (one of the consequences of "trading with the enemy"). Plenty of other tour operators continue to offer holidays in Cuba, but a leading chain of British travel agencies is set to stop selling them.

The imminent takeover by the US company Carlson of the tour operator Inspirations will mean that all branches of the travel agent AT Mays become American-owned. As soon as the deal goes through, AT Mays will stop selling Cuba.

Independent agents and operators will continue to risk the wrath of the White House by selling holidays in Cuba, and independent-minded travellers will continue to buy them. Should you book a seat from Gatwick to Havana on the Cuban national airline, you will find the aircraft used will be a DC-10 - manufactured in Long Beach, California. Mr Clinton's embargo must be alarmingly leaky if it allows a plane that size through the net.

"Your piece on black markets in Eastern Europe brought back many memories," writes Neil Taylor from Bristol. Mr Taylor is managing director of Regent Holidays, which has been offering holidays to odd places for three decades - many of which, until recently, offered the sorts of advantageous parallel markets mentioned in this column last week. I miss the thrills and opportunity of the black market; Mr Taylor doesn't.

"Discussing the black market with clients was a no-win situation, rather like discussing sex with teenagers: if you ignored the subject altogether, sudden unprepared exposure could lead to disastrous consequences; if you raised it, perhaps the temptation to experiment was equally fraught.

"I read the story over a beer and sandwich in Prenzlauer- berg, a Bohemian quarter in former East Berlin - where, in the mid-Eighties, black-market books and tapes were just as important as Western currency. I can't say I miss the black market, now that prices in Berlin have fallen, and good exchange rates are equally available from cashpoints, exchange bureaux and banks. And, of course, Sterling is strong all over the former communist world."

Given American sensitivities, I shall not name the individual who suggested that the best black-market anywhere involves smuggling Havana cigars into the US, where aficionados will pay a fortune for the real thing.