Historians have disputed an auction house's claim that it has the oldest-known letter sent from Hong Kong, causing the lot to be withdrawn from sale last week.
The letter - written by John Robert Morrison, a son of the first protestant missionary in China, Robert Morrison - was dated 1839, two years before British colonial rule began in Hong Kong.
Auction house InterAsia had estimated it would fetch up to HK$300,000.
But before the letter went under the hammer last Sunday, a European historian wrote to the auctioneer, claiming there could be an earlier letter, InterAsia's business development director Rob Schneider said.
The other letter, dated 1838, was sold in a group lot in an earlier auction, he was told.
"We have withdrawn the lot to do more historical research," Schneider said. He did not name the historian, but said the man was well-respected in the field.
The letter was the only lot withdrawn from InterAsia's stamp auction featuring 3,600 lots from January 11 to 14. The auction fetched HK$81.8 million.
The letter's author, J. R. Morrison, was among a group of Britons expelled from Canton before the opium war. He was on board a British naval ship anchored in Hong Kong waters at the time of penning the letter to his sister.
University of Hong Kong history professor John Carroll said the expelled Britons were not the first foreigners who sailed offshore of Hong Kong.
Non-Chinese mapmakers had charted the islands southeast of Lantau by the late 1700s, and in the early 1830s, foreigners were using Lin Tin island, between Hong Kong and Macau, for unloading opium, he said.
Some of those merchants should have been in Hong Kong territory, he said.
"It's highly likely for someone to have sent letters from there."