The only known copy of an insurance ledger covering the hull of the RMS Titanic during its sea trials is to be sold this month at auction.

The policy provides $US100,000 of coverage to the steel hull under the Atlantic Mutual Insurance Company.

The binder was signed on March 27 1912 – just 19 days before the ship sank during its maiden voyage from Southampton in England to New York, killing 1500 people. The policy limits were paid within 30 days of the sinking.

The ledger will go under the hammer at Henry Aldridge and Son auctioneers in Wiltshire, England, on November 21, with an estimated sale price of £30,000-£50,000 ($58,000-$97,000).

Atlantic Mutual was the largest US marine insurance company and is believed to have provided more coverage for the Titanic than any other individual carrier.

The policy provided coverage for a year from March 30 1912.

The auctioneer's website says: “Perhaps the most poignant and historically significant part of the document is an important handwritten addendum which states, in full: ‘To include the trip from Belfast to Southampton sailing on or after March 31 1912 ... and the risk of trials on said trip if any.’

“This note ensures the coverage also covered the ship’s delivery to port, making it a rare record of the ship’s protection before it carried passengers.”