The only surviving letter believed to have been written on board Titanic is expected to fetch up to £100,000 when it goes under the hammer today.

The letter, written on Titanic stationery, was written by second class passenger Esther Hart just hours before the liner struck an iceberg on Sunday April 14, 1912.

1,500 passengers and crew lost their lives in the tragedy, including Mrs Hart's husband Benjamin.

The letter, headed On board 'Titanic', comes complete with an envelope embossed with the White Star Line flag.

In the letter Mrs Hart, who was travelling with her daughter and well-known survivor Eva Hart, talks about being ill while on board the New York-bound liner.

Daily Echo:

Mrs Hart writes: ''My Dear ones all. As you see it is Sunday afternoon and we are resting in the library after luncheon. I was very bad all day yesterday could not eat or drink and sick all the while, but today I have got over it.''

She goes on to describe how she had been to a church service with Eva and to talk about the trip so far.

''Tho they say this Ship does not roll on account of its size. Any how it rolls enough for me, I shall never forget it. It is very nice weather but awfully windy and cold. They say we may get into New York Tuesday night but we are really due early Wednesday morning, shall write as soon as we get there'', she writes.

The letter was due to be delivered to Mrs Hart's mother in Essex when the ship returned to Southampton, but the tragedy meant it was never sent.

Mrs Hart and Eva were among those rescued by HMS Carpathia.

A biography by Eva Hart, which is also due to go under the hammer alongside the letter, recalls the moment her mother later found the letter in the pocket of her husband's coat.

Andrew Aldridge, from Henry Aldridge and Son Auctioneers, said the letter was expected to fetch between £80,000 and £100,000.

He said: ''The importance of this legendary item cannot be overstated, being the only known surviving example of its type to have been written on that fateful day, surviving the sinking, and having belonged to such a well-known survivor.

''The letter and envelope are in remarkable condition, with an impeccable provenance, and they represent a truly unique opportunity to own the finest example of its genre in existence. It is quite simply the jewel in the crown of Titanic manuscript ephemera.''

The items will go under the hammer with other Titanic collectibles at Henry Aldridge and Son Auctioneers in Devizes, Wiltshire.