The letter was written by first-class passenger Alice Lennox-Conyngham as the ship sailed from Southampton to Cherbourg, France, in 1912.

The folded piece of A4 paper, complete with its original envelope, is to be auctioned by Tennants of Leyburn, in North Yorkshire on 25 February.

It was part of the last consignment of mail from the Titanic before it sank.

Tennants valuer Diane Sinnott said the letter was valued at ￡6,000 to ￡8,000, but could fetch up to ￡20,000 in the sale.

In the letter to her nephew, Miss Lennox-Conyngham said the liner narrowly avoided a collision even before it left Southampton.

"There was nearly an accident just as we started but we did not know till it was nearly over," the letter on RMS Titanic paper says.

"It is a vast place - five decks, immense drawing rooms, dining rooms and swimming baths and gymnasium - and a band playing."

She mentions the weather, saying: "It's rather cold but not too bad."

The letter, dated 10 April, 1912, is being put up for sale by its owner, Christian Duff, the daughter of Miss Lennox-Conyngham's nephew.

It was postmarked a day later, just three days before the liner hit the iceberg and sank.

Miss Duff was unaware of its potential value until a chance remark she made to Ms Sinnott.

"The lady had no idea it was worth anything and it was being used as a bookmark," Ms Sinnott said.

"It still has its original envelope, with its stamp and postal cancellation marks on it. It's also got good provenance."

（Agencies）