The decline of the pound against the euro and dollar has created a headache for the Bank of England as the inflationary impact on imports has acted as a counterweight to arguments for interest rate cuts to head off recession.

But even as the cost of dollar and euro-denominated oil, commodities and food stuffs have hit UK consumers and companies reliant on imports, the fall of sterling has boosted the revenue and profits of many British companies whose sales are mostly generated overseas.

The translational boost has not been overlooked by investors.

The share price of London-listed Shire, the pharmaceuticals company with 88 per cent exposure to the US, sank for much of this year but it has recovered sharply since the summer as the dollar made gains.

Other US-focused UK companies such as Wolseley, the builders supplier, and the jewellery retailer Signet, whose shares have suffered amid a US construction and consumer spending downturn, have also climbed in recent weeks.

In a research note last week, UBS noted that in the six-week period from July 17 when sterling’s decline against the dollar began, 85 per cent of companies with a high exposure to the US had outperformed the market.

The note’s author Gareth Evans suggests, notwithstanding concerns over the state of the US economy, the prospects of a strengthened dollar could provide opportunities for investors prepared to upweight their holdings in stocks with high exposure to the world’s largest economy. According to UBS, 24 per cent of sales for the FTSE 100 were made in the US in 2007, and 17 per cent for the FTSE 250.

For many companies and sectors this exposure is far higher, with the industrial engineering, aerospace and defence, healthcare equipment, auto parts and pharmaceuticals sectors enjoying US sales ranging from 35 per cent to 56 per cent of their totals.

And it is these sectors that have generally outperformed the market since mid-July. Meanwhile other sectors with more exposure to the softening UK domestic market – such as travel and leisure, and retailers – have continued to lag behind.

But the extent of currency gains also varies considerably depending on whether goods and services produced by UK-listed companies are produced domestically or in non-sterling zones.

Many UK companies with large US sales also have large US operations, meaning sales gains translated into sterling are largely dissipated by higher costs of sales and production when measured in pounds.

According to Robin Savage, analyst with KBC Peel Hunt: “Traditionally you bought businesses that were exporters, dollar revenue generators but the people were paid in sterling. But, for example, most engineers have ‘re-engineered’ their business to make sure they are less sensitive to currency swings by moving the production where the revenue is from.”

Dollar gains can also be dissipated by overseas debt costs.

Ashtead, the equipment hire group that does most of its business in the US, said this week that virtually all its debt was in US dollars.

With $1.7bn (£957m) outstanding and a strict repayment schedule, having to pay off that debt will partly offset the tailwinds the company was expecting in coming months as its US dollar earnings are converted at more favourable rates.

UK companies reliant on dollar-quoted oil and other commodities are also expected to suffer from sterling’s weakness against the greenback.

British Airways pointed out this week that industry conditions remained difficult, “with the strong dollar largely offsetting the benefit of the recent fall in oil prices”.

The inflationary impact of sterling’s fall may be a boost to exporters, but it limits the Bank of England’s scope to cut interest rates while it hurts companies selling into the domestic market, says Simon Hayes, economist at Barclays Capital.

For others, the weakening of sterling against the dollar provides a welcome respite after years of suffering.

Smaller companies such as Tarsus, the business-to-business group, is typical of those with unhedged US exposure.

“Two-thirds of our profits are dollars so we’ve been absorbing all that dollar pressure for the last two years,” says Doug Emslie, Tarsus chief executive. “Suddenly, thankfully, sterling has been in rather rapid retreat.”

Many of the companies set to benefit from the recent rise in the dollar also have large exposures to the euro. And with Europe remaining Britain’s most important export market, sterling’s longer-standing weakness against the euro is already boosting results.

For example Aegis, the media and market research company, managed a boost in interim revenues of 22 per cent to £608m. Eight per cent of the gain was currency-related. Pre-tax profits at Aegis, which benefited from a 33 per cent exposure to the euro, rose by 18 per cent to £47.4m – though at constant exchange rates profits stood still.

But while many companies themselves admit to a worsening trading outlet on the continent as eurozone economies soften, currency traders and economists also counsel that the euro’s strength against sterling has peaked.

Companies gaining from the strong euro have also cautioned over signs of a slowdown going forward.

After the US, Britain’s big trading partners are Germany, France, Ireland, Netherlands, Belgium, Spain, Italy and Sweden. As a result any European slowdown will adversely affect the UK, argues George Buckley, chief UK economist at Deutsche Bank. “The UK is in a very fragile position,” he says.

Additional reporting by Robert Cookson and Stanley Pignal