The National Library has found Australia's first pound note, thought to be lost to history for nearly 80 years, in its very own archives.

The note, marked with the serial number P000001 was the first piece of currency to carry the Australian Coat of Arms.

Despite its significance, the note's discovery came about purely by chance.

A coin dealer, looking to sell Australia's first 10-shilling note to the library, alerted them to his suspicions that the note lay within their collection.

That sparked a search of the National Library's myriad of manuscript files.

"The manuscript collection altogether has 12,000 collections and some of those collections are one item or one box. Other collections have many hundreds of boxes and thousands of items," curator Kylie Scroope said.

"The first place we started looking was in the personal papers of then prime minister Andrew Fisher.

"We knew that Mr Fisher had an association with the establishment of this currency, and the printing."

The search of Mr Fisher's personal papers turned up nothing, so the search widened to the entire collection.

"Then it became a matter of using the library's catalogue to search for any collection that had a description that made reference to currency or banknote," Ms Scroope said.

Eventually the note was found in a collection said to contain specimen bank notes.

"My understanding is they aren't currency that has gone into circulation, they are produced as an example or master," Ms Scroope said.

"[But] the Fisher note is in fact not a specimen and there was no reference to Mr Fisher or it being the first note in the catalogue description."

Ms Scroope said the design of the note was fairly simple.

"It does say Commonwealth of Australia one-pound note," she said.

"I think one of the curious things on it is that it makes reference to the bearer being able to redeem it at the Treasury for the equivalent of one pound in gold which creates lovely pictures in my mind of someone turning up to Treasury with their note and asking for a pound's worth of gold."

Ms Scroope said while the exact value of the note was unknown, she expected it to be worth more than $1 million.

"Based on sales of comparable items with similar rarity and provenance and age, then we expect that it would reach something well over $1 million."

Note 'lost' among other treasures in library's collection

The one-pound note was presented to Mr Fisher by the Treasury in 1913.

NLA curator Kylie Scroope said the rare note was uncovered after an extensive search of the Library's collection. ( ABC News: Ian Cutmore )

He kept it until 1927, when he passed it on to then prime minister Stanley Bruce, for donation to the Parliamentary Library.

"The Parliamentary Library and the National Library at that stage were a single institution," Ms Scroope said.

Despite records of the donation at the National Archives of Australia, the note went largely unnoticed for the next 80 years.

But Ms Scroope said someone must have found the note in the archives and placed it into a conservation sleeve sometime in the past 30 years.

"In the 20 or 30 years since those sorts of materials came about, but we don't know when that happened," Ms Scroope said.

She said it was difficult to tell what other treasures may be in the National Library's possession.

"Until someone starts looking in the boxes you never know what might be lurking there."

The note is set to go on public display at the library from Monday.