THE only known letter to have been written on board the Titanic on the day the liner struck an iceberg is to fetch as much as £100,000 when auctioned this month.

Written by survivor Esther Hart, but never sent, the letter had been intended to be delivered to Mrs Hart's mother in Chadwell Heath in Essex at the end of what would have been the Titanic's return journey to Southampton in April 1912.

The letter, and its envelope, were acquired 20 years ago by a man who has now passed it on to Henry Aldridge & Son auctioneers of Devizes, Wiltshire, with the letter coming under the hammer on April 26.

The letter is embossed with the White Star Line flag and is headed On Board RMS Titanic and dated "Sunday afternoon".