Investors will be scouring results from some of Britain's biggest companies next week to see the impact of the economic slowdown on earnings.

Barclays is expected to report a five per cent slip in pre-tax profits to £1.88bn on the back of rising costs when it reports on Thursday, fund manager Gerrard forecasts.

The City will be keen to ask about its exposure to struggling corporates and beleaguered industries in the current market turmoil.

Media group Pearson's business is heavily weighted towards the second half of its financial year, so figures for the first half are forecast to show a small loss when it reports on Monday, against a £5.3m profit last time.

The group's newspaper business has suffered in the advertising downturn and analysts do not expect a recovery at its FT Group business this year, which includes the Financial Times as well as newspapers abroad.

In February, BP reported a sharp fall in quarterly profits as demand for oil and gas tumbled in the face of the economic slowdown, and after the oil price fell.

Second-quarter figures, due on Tuesday, are also expected to show a slide, to $2.06bn (£1.3bn) against $3.43bn (£2.2bn) last time.

Rival Shell's last quarter figures also showed a slide for the same reasons as BP. Its second-quarter figures, out on Thursday, are forecast to show a slide in pre-tax profits, down to $2.42bn (£1.55bn) against $3.52bn (£2.26bn).

Production volumes, however, should see a boost as Enterprise Oil, which it bought earlier this year for £3.5 billion, is integrated into the second-quarter numbers.

Anglo-Dutch group Unilever is forecast to report second-quarter pre-tax profits of £1.9bn on Wednesday, up from £1.5bn.