The former Cunard White Star liner, built by John Brown's on the river Clyde, is up for sale and must find a new operator if she is to be assured of survival. Now a hotel and museum in Long Beach, California, she has become a loss-making white elephant in danger of extinction.
Some 800,000 people visited her last year - a large number, but not enough to pay for the upkeep of an 81,237-ton vessel with 12 decks, miles of impeccably carved woodwork and an ageing, barnacle-coated hull. Since taking her over in 1988, her operator, the Walt Disney Company, has lost dollars 5m ( pounds 2.5m) or more on her every year. When coastal commissioners blocked Disney's plans to build a maritime theme park around the ship, the company decided enough was enough. It declined to renew its lease.
The Queen Mary's owner, the Port of Long Beach, has decided to close the ship's hotel in September, keeping the rest of the vessel open while the search for a new lessee or buyer continues. The move is widely seen as a possible first step to total closure next year.
That would be a humiliating end to a glorious career which began in 1934 when 200,000 people lined the banks of the Clyde to see the launch of a ship that had come to symbolise the national will to defeat the Depression. Queen Mary herself was there to name the vessel - the first time a reigning queen had performed such a ceremony - and King George V spoke stirringly of 'the stateliest ship now in being'.
On 27 May 1936, she set sail on her maiden transatlantic voyage, carrying 2,000 passengers (in three classes) from Southampton to New York. It was one of the biggest events of the year, a story that oozed so much glamour that the BBC decided to broadcast from her during the voyage.
This was an era when suitcases were suitcases, and luxury meant luxury. Even third-class passengers had a choice of five hors d'oeuvres with their evening meal, sustenance for days spent playing shuffleboard, deck quoits and ping-pong.
They could get a Turkish bath with alcohol rub for ten shillings (50p), before travelling - by lift - up to the barber's shop for peroxide treatment to remove freckles.
At times the passenger manifest could have been copied from the credits of Hollywood's finest films. Fred Astaire, Gary Cooper, Gloria Swanson, Bob Hope, Harpo Marx, Joan Crawford, Alfred Hitchcock, Mae West, Walt Disney. Rachmaninov insisted on being given a special soft-pedalled piano. The Duke and Duchess of Windsor would arrive on board with 60 pieces of luggage. The Duke would fritter away the hours driving golf balls out to sea.
This glitzy existence was suspended during the war when the Queen Mary was converted into a troopship, carrying up to 15,000 servicemen across the Atlantic at any one time. Here her speed, which had won her the Blue Riband in 1938 for the fastest Atlantic crossing, was a distinct asset.
Cruising at 28.5 knots she outran escorts and U-boats, and survived the war without being fired on. However, she became involved in one tragic incident - hushed up until the war's end - when she ran down her cruiser escort HMS Curacao, with the loss of more than 300 lives. The Queen Mary sustained only a dented bow.
In the end, it was the growth of air travel that stole her crown. By 1967, business was so bad that Cunard was forced to sell her to Long Beach for dollars 3.45m, consigning her to an uncertain future in a fast-growing society not known for its fascination with British relics. Since then she has passed through a handful of different operators, and has cost Long Beach dollars 25m in subsidy.
These days, if you visit the ship, you can measure the cultural gap, the distance travelled between then and now. Her three fat funnels jut up into the smog-hazed sky. She rises up and down with the tide, protected from the swell by a breakwater. Seagulls besmirch her railings. Pelicans flop by, flying low over the milky blue water. Tourists in fluorescent shorts, and baseball caps worn backwards, pad about the decks with video cameras.
There are red British telephone boxes on deck, fast-food outlets and shops with names like Her Majesty's Sweet Shoppe. Youthful Disney guides, buoyant in their peaked sailor hats and braided blazers, bound noisily along the endless corridors.
Although Disney eventually invested in some repairs, parts of the ship are tatty. Someone has carved a love heart on one of the funnels (which, in an effort to brighten her up for the modern consumer, has been painted the wrong shade of red).
David Young, a medical worker from Washington state, last week boarded the Queen Mary to pay what may be his final respects. He rummaged around in his rucksack and carefully withdrew a piece of paper. It was a cabin-class ticket, New York to Southampton, dollars 192 round-trip, 1964.
'That trip ranks as one of the best times I can remember at any stage of my life,' he said. 'It was very romantic. This ship was a modern version of the great sailing ships, part of life's experience for many generations. What's happening now is very, very sad.'
But many Californians have little patience with loss-making ventures, especially when they are not of their own making. The Golden State does not much like losers. 'We are used to the passing of things,' said Forrest Glen Owen, from Los Angeles, another visitor. 'I say if it's not making any money, shut it down.'
The crisis may yet be happily resolved. The Long Beach Harbour Commission has not abandoned hope, and last week even sounded optimistic. Its spokeswoman, Yvonne Avila, said it had received between 50 and 60 commercial proposals for the ship, ranging from the serious to the eccentric. These included several schemes to convert her into a Las Vegas-style gambling venue - a move that would require a change in Californian law, which outlaws most forms of gaming. A Japanese concern submitted plans to convert her into an office block, she said.
Some of the schemes, which are being scrutinised by a financial consultant, include plans to tow the Queen Mary elsewhere. Staff on board say this would be a tricky operation, and might require her hull to be strengthened. She has no boilers and most of her engines have been stripped out.
Ultimately, the shadow that hangs over her fluttering pennants is that of the scrapyard, even though the cost of breaking her up would far exceed the income from her parts. 'That is an option none of us would like to take,' said Ms Avila. 'What we would like is someone who would operate it at a profit or buy it.'
When the Queen Mary's first captain, Sir Edgar Britten, set off on her maiden voyage, he said he was sure the ship would be 'a link between two great English-speaking peoples'. History has seen fit to organise events differently. It is all too easy to imagine this once great vessel rotting away on the Californian skyline, an undignified memorial to a culture that doesn't much care.