Americans coming to London these days are well advised to bring bags full of that once-valuable currency, the U.S. dollar. And some Americans living here may soon have to put out the begging bowl.

The recent dramatic plunge in the value of the dollar has had an impact worldwide, but the pain is especially acute in London, which ranks near Tokyo as one of the world’s most expensive cities.

When I lived here in the early 1980s, the dollar was robust and once briefly touched $1.10 to the pound. When I retired in 2001, it stood at around $1.62. Today’s rate is $1.88, a drop of 16%.

The dollar’s weakness may have little effect on dollar-salaried Americans working here for American firms, for they usually get cost-of-living allowances. The big shock has been felt by their employers, retired Americans living here, and visitors from America.

For visitors, the pain starts with the taxi ride from Heathrow Airport, which can cost $90 or more. Visitors can always find deals on hotels, but London’s most-prestigious hotels may charge between $360 and $450 for a double room in winter, $415 to $515 in high season.

Dinner for two with wine in run-of-the-mill restaurants costs about $90. Dinner in a first-class restaurant runs to more than $200, and in one of the handful of three-star restaurants, the bill will easily top $300.

The best seats in a London theater cost about $75 each, but prices for musicals are higher. So an evening for two that includes theater and dinner can easily run to $350, not including taxis or other incidentals. Tickets for two adults to the movies cost $30, but for senior citizens the price is $22.

With our budget, some things that were once occasional treats are now just memories, such as tickets for two to the Royal Opera at around $650. Granted, those are the best seats in the house and the opera tries to combat an elitist image by offering seats “in the gods,” the farthest reaches of the upper balcony, for just $7.50 or $15. But who can see or hear anything from there? The English National Opera, where operas are sung in English, charges a top price of $225.60 for two.

Americans complain about paying $2 a gallon for gasoline, but in Britain, and in continental Europe, the price has been more than twice that since the oil shocks of the 1970s. My car has a 13-gallon tank and it costs me about $76 to fill it. I don’t drive much any more.

I haven’t calculated our weekly grocery bill lately, but newspapers assure us that Britain has the highest grocery prices in Europe. The same is true for getting a car serviced, or for buying heavily taxed wine and liquor.

So I go to France for car service and booze, and a bit of food shopping. Even after paying about $70 for a roundtrip, same-day Channel crossing by train, and indulging in a splendid French lunch in Calais for as little as $35, I still save money. British Customs allows each resident to bring back about 90 liters of wine – that’s 120 bottles – for personal consumption. Go beyond that and they assume you intend to sell it, which is illegal, and penalties have included confiscation of cars or trucks used to haul the booze.

I particularly appreciate the saving on Jack Daniel’s whiskey, which costs about $45 for a 1-liter bottle in London and $30 in Calais.

My London car dealer charges close to $400 for the annual service. In Calais recently I paid $205.

London prices are stiff even for those on pound salaries, and newspapers here delight in comparing “rip-off Britain” with other major cities. Each year some Britons find cheap weekend flights to New York, do their Christmas shopping there, and still save money.

They rejoice while I weep. If some day you find a miserable-looking American standing on a London street with his hand out, rest assured I will not be saying: “Brother, can you spare a dime?” A dime is worth just 5.3 pence. Even a dollar won’t buy a cup of coffee in this town.

Mr. Moseley is a veteran foreign correspondent who covered the world for the Chicago Tribune for several decades. He was recently made a Member of the British Empire.