IT is almost 91 years since the sinking of the Titanic and its terrible loss of life plunged both sides of the Atlantic into mourning.

When the unthinkable happened to the supposedly unsinkable pride of the White Star Line, on a freezing April night in 1912, it became an instant legend.

Items associated with the doomed liner are in huge demand among collectors, and a new find is causing excitement - a letter from a first-class passenger to her nephew in England.

The letter's owner, the nephew's daughter, who lives in the Darlington area, believed for years that it had only nostalgic value, so she used it as a bookmark. But after a chance encounter with a valuer from Tennants Auctioneers, she discovered it was highly collectible and worth about £7,000.

Written on Titanic-headed notepaper and in its White Star envelope, the letter was written on Wednesday, April 10, 1912, by a Miss Alice Lenox-Conyngham, holder of ticket number 75.

She was travelling with her sister-in-law and two children on the first leg from Southampton to Cherbourg, the ship's first port of call, when she decided to write to her young nephew in Cambridge.

They disembarked in France but the letter was not posted until the next day, when the Titanic made her second - and last - stop, in Ireland at Queenstown, now known as Cobh.

In the letter she describes the ship: "It is a vast place. Five decks, immense drawing rooms and dining rooms and swimming baths and gymnasium - and a band playing..."

She also refers to a near-miss as the ship left Southampton: "There was nearly a collision just as we started but we did not know 'til all was over," she wrote.

The letter will go under the hammer at Tennants' Leyburn auction rooms, North Yorkshire, at a book sale on February 25. International interest is anticipated.

Valuer Diane Sinnott said: "The owner nearly fell off her chair when she discovered what it was worth."

Items associated with the Titanic are highly collectible, particularly in the US and especially New York, where the ship was headed but never arrived, she said