Mowbray Collectables assessor Ken Markham said the letter was sent from the Legislative Council Chamber in Wellington on July 4, 1856, advising Cargill of proceedings from Parliament.
He was the founder of the Otago settlement in New Zealand, a member of Parliament and Otago’s first superintendent.
"Parliament was set up in Wellington in 1854, so they were really just getting into the swing of things," Mr Markham said.
"I presume he was an absentee member, and being from Dunedin, it wasn’t easy for him to get to Wellington.
"The only way to get there would be by ship and it wasn’t always easy to get into Wellington Harbour."
Mr Markham said the letter was an important piece of New Zealand history and was one of many items which would go up for auction at Mowbray Collectables in Wellington.
"It’s important because William Cargill and Thomas Burns were involved in the establishment of Dunedin.
"Between them, they set the whole city in motion.
Mowbray coins, banknotes and medals director David Galt said other Otago-related items in the auction included an Otago miner’s rights document, dated October 10, 1862, for mining at Waitahuna; and an envelope addressed to Choie Sew Hoy from the
Waitahuna gold fields, among other letters from the Otago goldfields.
There was also a rare communion token from Kakanui up for auction.
"These tokens were traditionally given to Presbyterians to make sure that they were eligible to receive communion — originally a matter of safety after the 17th century English Civil War when Presbyterians were on the losing side, but then became a matter of tradition that came to New Zealand with Scottish settlers.
"Many were issued in Otago in Presbyterian churches.
"The Kakanui token is estimated at $1250 because it is so rare.
"There are also unusual examples from North Taieri and Oamaru in copper when most were made in lead or pewter."
Mr Galt said the 1363 lots up for auction were in total estimated to be worth more than $1.25million.
The top estimate of $18,000 is for a set of six New Zealand coins from 1935 including a crown depicting William Hobson and Chief Tamati Waka Nene at the signing of the Treaty of Waitangi.
