Fifteen hundred passengers were lost when the Titanic went down

Several personal effects of Dumfries man Thomas Mullen, a third-class steward, were contained in the box.

It was bought for �102 in a local sale room before Christmas.

The items are now expected to fetch 500 times more - about �50,000 - than the initial price when reauctioned.

The buyer does not want his details made public but Alan Aldridge, from an auction firm which specialises in Titanic memorabilia, explained what happened.

'Gobsmacked'

He said: "He saw this postcard being offered and it said in the auction room that it had a Titanic connection to Mr Mullen.

"He asked the auctioneer what it was likely to fetch and the auctioneer gave him an opinion and from that he left a bid of �102, not really expecting to get it.

"He later found out that he'd been the winning bidder."

Mr Aldridge added that had he been the salesman in the Dumfries auction room, his valuation would have been a great deal higher.

"I'd set its value at between �40,000 and �60,000. When I told the buyer this valuation when he brought them to me, he was certainly pleasantly surprised - gobsmacked is probably a better word for it."

The postcard which attracted the unnamed buyer's attention was an official Titanic one posted to Thomas Mullen's brother from the US by a survivor five days after the ship sank and containing details of the disaster.

'Healthier return'

Also inside the box was a metal brass badge with a star on the front, a leather case, a damaged silver watch and a damaged case.

Mr Aldridge is now appealing to the individual who sold the items for next to nothing to come forward.

He said: "It's a tragedy for the person that sold this stuff in the first place but we know there are at least another five items out there relating to Mr Mullen and these items are somewhere in Dumfries or somewhere in the rest of the country.