A gold pocket watch recovered from the body of one of the richest passengers on the Titanic is expected to fetch £1m ($1.3m) at auction.

Isidor Straus and his wife Ida, were among the more than 1,500 people who died when the vessel travelling from Southampton to New York sank after hitting an iceberg on 14 April 1912.

His body was recovered from the Atlantic days after the disaster, and among his possessions was an 18-carat gold Jules Jurgensen pocket watch that will go under the hammer on 22 November.

Auctioneer Andrew Aldridge, of Henry Aldridge & Son in Wiltshire, told BBC Radio Wiltshire: "With the watch, we are retelling Isidor's story. It's a phenomenal piece of memorabilia."

Mr Straus was a Bavaria-born American businessman, politician, and co-owner of Macy's department store in New York.

"They were a very famous New York couple," said Mr Aldridge.

"Everyone would know them from the end of James Cameron's Titanic movie, when there is an elderly couple hugging as the ship is sinking - that's Isidor and Ida."

On the night of the sinking, it is believed his devoted wife refused a place in a lifeboat as she did not want to leave her husband and said she would rather die by his side.

Ida's body was never found.

The pocket watch stopped at 02:20, the moment the Titanic disappeared beneath the waves.

It is believed to have been a gift from Ida to her husband in 1888 and is engraved with Straus' initials.

It was returned to his family and was passed down through generations before Kenneth Hollister Straus, Isidor's great-grandson, had the movement repaired and restored.

It will be sold alongside a rare letter Ida wrote aboard the liner describing its luxury.

She wrote: "What a ship! So huge and so magnificently appointed. Our rooms are furnished in the best of taste and most luxurious."

The letter is postmarked "TransAtlantic 7", meaning it was franked on board in the Titanic's post office before being taken off with other mail at Queenstown, Ireland.

Both items will be offered by Henry Aldridge & Son in Wiltshire, with the letter estimated to fetch £150,000.

The watch is set to become one of the most expensive Titanic artefacts ever sold.

The auction house said news of the sale had already generated "significant interest from clients all over the world".

"Theirs was the ultimate love story - Isidor epitomised the American Dream, rising from humble immigrant to a titan of the New York establishment, owning Macy's department store," a spokesperson for the auction house said.

"As the ship was sinking, despite being offered a seat in a lifeboat, Ida refused to leave her husband and stated to him, 'Isidor, we have been together all of these years, where you go, I go'."

The spokesperson added: "This is the reason why collectors are interested in the Titanic story 113 years later - every man, woman and child had a story to tell and those stories now are retold through these objects."

A gold pocket watch presented to the captain of the Carpathia, the steamship which rescued more than 700 Titanic survivors, sold last year for a record-breaking £1.56m.