The troubled cruise line is expected to be put up for sale if takeover talks succeed between its equally battered parent, Trafalgar House, and Norwegian shipbuilding and engineering group Kvaerner.
Erik Tonseth, Kvaerner's chief executive, is expected to decide this week on whether to make a pounds 900m bid, worth between 50 and 55p per Trafalgar share, after surprising the market with news of the talks last Tuesday.
Sources close to Kvaerner - which last year lost a hostile pounds 360m bid for UK construction and engineering firm Amec - said it was mainly interested in Trafalgar's engineering and contracting businesses and would want to dispose of its housebuilding, commercial property and shipping divisions.
Asked at the weekend if he would be interested in buying, Lord Sterling, P&O chairman, said that if Cunard were offered, "We would be prepared to look at it, at a price." P&O's two biggest rivals, Carnival and Royal Caribbean, might also be interested.
Sale of Trafalgar would be embarrassing for Hong Kong's powerful Keswick family, whose property arm, Hongkong Land, rescued the group in 1992. It would, however, mark an end to a disastrous involvement, which has seen more than pounds 200m pumped into a black hole - losses reached pounds 321m last year.
Cunard has long been up for sale, and any deal now could founder on the rocks of P&O's shareholders, who are already disappointed by its poor financial performance and want to avoid any further problems.
"It would be another nail in the P&O coffin," said one disgruntled fund manager. "There's probably not much we can do about it right now, though. They could probably get a bank to lend them the money without any equity backing." But it would hit the shares and make investors far less likely to respond the next time they are called upon.
Although Cunard has a well-known brand name, particularly in Britain and the eastern US, its assets are considered by many observers to be second-rate, out of date and accident-prone.
The flagship QE2 had a disastrous voyage 15 months ago, when it set sail in the middle of a refit, resulting in pounds 8.4m of refunds to angry passengers. Last week, more bad press came when fire broke out on the liner Sagafjord, leaving it adrift in the South China Sea with 500 people on board.
Industry insiders think Cunard's eight ships would probably fetch less than pounds 200m, and another pounds 1bn would have to be pumped in to bring them up to rivals' standards.
Its big advantage over P&O is its brand name and market share, plus the economies of joint marketing and administration.
However, P&O's shareholders fear that a Cunard bid would only delay long-promised returns from it own upgraded fleet. P&O's flagship Oriana and a small squadron of super luxury liners in the Princess class are only now starting to contribute to the bottom line. Re-equipping Cunard could add three years to the process.
"They keep telling us that things will get better soon, but buying Cunard would put 'soon' back a number of years," said one fund manager.