The gap between the FTSE 100 and the Dow Jones Industrial Average, which traditionally travel in tandem, is at its widest for more than a decade.

The Dow has risen 45 per cent from its low point last year, while the Footsie has gained only 26 per cent, prompting speculation that the special relationship between the two markets might have ended.

The trend has accelerated largely because of the Internet explosion. It adds impetus to news last week that Tony Blair has backed a report that attacked British companies for their slowness in grasping commercial opportunities offered by the Internet.

"The US was effectively ring-fenced from the Russian and Asian crises and, more importantly, it's very difficult to get a piece of the technological revolution if you don't invest in the US," says Mr Robert Buckland of Salomon Smith Barney. "The nearest we get is Vodafone. We have nothing like Microsoft or even IBM."

Although the Dow contains no Internet stocks, it has been pumped up by related buying as well as a surge in online investing by private individuals.

The other reason is fundamental economics. The divergence began in the mid-1990s when the US market responded to 4 per cent GDP growth while the Footsie reflected a more sluggish situation that has seen British growth slip to 1.5 per cent this year.

Mr Khuram Chaudhry, equity strategist at Merrill Lynch, says there is a self-feeding "wealth effect. As the economy grows stronger, people own more of the stock market and earn more money from the stock market so they have more money to put into the stock market".

Over the past decade, the Dow has outperformed Britain's blue-chip index by more than 50 per cent in dollar terms. A broad $1,000 (€940.82) portfolio of Dow stocks invested in 1989, two years after the global equity market crash, would be worth $4,100 today, while a British pension fund investing the same amount in the Footsie would have increased its holding to about only $2,700.

This gap could provide a cushion for Britain following the rise in US interest rates this week. Mr Chaudhry says that on most valuations the US stock market is more expensive than it has been for a decade while Britain is - if not cheap - at least fair value.

The current price/earnings multiple of the Dow is 34 times, compared with 28 times for the Footsie. The US equity earnings yield ratio, which compares the equities to bonds, is at levels not seen since 1987 or shortly before the bond crash in 1994 while in Britain it is far less stretched. That could be positive for Britain if there were a big shake-out in New York.

Chart analysts see two elements in the US-Britain divide and argue that the short-term patterns are masking a persistent drift.

Mr Ian Rankine, technical analyst with Durlacher, the private client stockbroker, says: "On an intraday basis, all we have to look at is the Dow and we follow it slavishly. On a slightly longer-term view we have decoupled and the trend away will continue. To a certain extent we are being restrained by European markets."

Hopes of Britain and other European bourses experiencing an independent and belated eurosurge to return into line with the US are probably over-optimistic. On the other hand it is unlikely there will be a nation of Rockefellers on one side of the Atlantic and pleading Oliver Twists on the other.

Mr Buckland says: "About 95 per cent of the movement in UK prices can be explained by movements in the US, compared to only 50 per cent in the 1970s, and the US exposure to the UK doubled between 1992 and the last available figure in 1997. We remain a bit of a poodle."