Peninsular and Oriental Steam Navigation Co. is forecast to show a drop in operating profit from cargo shipping this year.

But a leading firm of analysts expects a slow recovery in 1994 followed by further improvement in 1995.A detailed study of P&O's various businesses by NatWest Securities concludes that there are a number of positive influences at work, such as the depreciation of British sterling and reduced losses on the North Atlantic, which should lift profits from shipping next year.

But NatWest Securities, one of the few firms that follows the shipping industry, warned that the poor freight rates in the important Europe-Asia container trades and a weak bulk shipping market earlier this year will depress 1993 profits.

P&O, Britain's largest shipping company, combines results for P&O Containers Ltd. and P&O Bulk Shipping Ltd., but container shipping is thought to account for most of the operating profit, which came to UK36.2 million ($55 million) last year, excluding receipts from ship sales.

NatWest Securities forecast that profit will drop in 1993 to UK26 million before climbing to UK34 million next year.

By 1995, the securities firm said it expects P&O's cargo shipping subsidiaries to be showing a combined profit of about UK40 million.

The analysts commented on how the behavior of the shipping lines will influence future freight rates and, in turn, earnings.

"There is the extraordinary situation of the rates weakness on the important Europe-Far East trades where ships are sailing virtually full," NatWest Securities said.

Once fears about economic prospects abate, substantial freight rates increases appear possible which could have a "very large" impact on profits.

P&O Containers, the seventh-largest container shipping line in the world, has a market share in the Europe-Asia trades of about 10 percent, NatWest Securities estimates. The trade accounts for around 40 percent of the shipping line's capacity and most of its profits.

While noting the potential for profit recovery if shipping lines take advantage of high cargo-load factors to raise rates, NatWest Securities said its forecasts only allow for modest freight rate increases.

On the Atlantic, the firm reckons that P&O Containers probably lost around UK10 million last year. Overall, the trans-Atlantic trade could return to

break even next year as long as there is no adverse interference from the European Commission, the firm predicted.