Sunken ship mementoes can rise from seabed and increase in price

There is nothing like a blockbuster film to bolster prices of collectables. The smash hit 1997 film Titanic, starring Kate Winslet and Leonardo DiCaprio, pushed prices for relics of the Titanic "through the roof", says Mr Peter Boyd-Smith, founder of Southampton-based specialist dealer, Cobwebs.

Items from the White Star Line, which owned the Titanic, rocketed by 50 per cent as new collectors clambered aboard. But when the new recruits lost interest and floated away, prices plummeted. Run-of-the-mill White Star dinner plates selling for up to £1,000 (€1,444) in 1997 now fetch £150 to £300.

But relics from the Titanic are still leagues ahead on collectability and value. "It's very much to do with the right boat and the right sort of time," says Mr Lionel Willis, marine specialist at auction house Bonhams.

Items with an added human interest - passengers' or crew's personal belongings as opposed to a generic piece of china - will be even more sought-after.

A first-class menu for the first dinner aboard the Titanic on April 1st, 1912, belonging to Fifth Officer Mr Harold Lowe, a much-lauded hero who returned to the wreckage searching for survivors, fetched £51,000 at auction last year.

A gold-plated watch from a passenger's body, which stopped at the moment the Titanic sank on April 15th, sold recently at auction for £18,000. A Titanic second-class passenger list fetched £26,000.

If your wallet cannot stretch that far, items from other early ocean liners, equally tragic but largely forgotten, are far more accessible. A menu from Cunard's Lusitania, sunk by a German U-boat off the Irish coast in 1915 with the loss of about 1,200 lives, costs £50. A porthole retrieved on a 1988 dive will cost £500 to £600.

A dining room plate from the Empress of Ireland (on which about 1,000 people died when it collided with a freighter off Canada in May 1914), will sell for £200. Ten years ago, it would have cost £100, so such items do gain value slowly.

Mr Andrew Aldridge of auctioneers Henry Aldridge, says: "Empress of Ireland and Lusitania memorabilia are incredibly undervalued. The Titanic has that allure about it."

The heyday of the ocean liner was before the second World War. After that, says Mr Willis, "the great glamour days of transatlantic travel petered out because people started flying."

Bone china made in the 1950s for the Queen Mary, which first sailed in 1936, and from her sister ship, the Queen Elizabeth, can be bought for £40.

Special occasion pieces can be worth collecting but beware of hype. Mr Boyd-Smith says that $30 (€23) T-shirts from the QM2's maiden voyage in January 2004 were soon selling for $300, but fetch only £20 now.

Provenance is the key: an item must be proven to be from a ship or from that era. So, buy now then pray that your ship comes in - in the shape of a blockbuster movie.

A menu from the Lusitania (left) fetches £50, while a plate from the Empress of Ireland may get £200. Prices for Titanic relics have fallen in recent years.