Paperwork which probably contained undercover secrets of Queen Victoria's reign could have been lost forever.
Queen Victoria knighted Pryce Jones in 1887
Crucial pages from a royal order book from a company thought to have supplied Britain's longest-serving monarch with underwear have been ripped out.
The discovery was made by an expert from Powys County Council's archives' unit who was given the task of cataloguing the business records.
It is unclear who has taken the documents and why.
The disclosure follows a warning from historian David Pugh last week who said "crucial documents" relating to the Queen may have already been lost.
The records had been gathering dust for more than 130 years at the former headquarters of the world's first mail order business in Newtown, Powys.
Powys County Council's archives unit said it had already catalogued 50 volumes of Pryce Jones' records and had another 20 to do.
"I found a royal order book, but all the pages had been ripped out," said archives manager Catherine Richards.
"We took possession of four crates of loose paper too and the documents could be in there, but it seems unlikely.
"Other records include accounts, local and national newspaper cuttings and minutes from meetings although there are surprisingly only a few of those documents.
"The Royal Welsh Warehouse (Pryce Jones' HQ) received an order for 60,000 blankets for the Russian army and Florence Nightingale had a special type of flannel made for her which carried her name."
Ms Richards added: "There are some royal warrants and a letter on behalf of Queen Victoria which are all framed.
"There's one warrant from 1880 from the Princess of Wales, one from 1902 from the Princess of Wales and another from Queen Alexandra in 1911.
"These give the right for the firm to supply the royals with woollen products.
"There's also a letter from St James Palace and one on behalf of Queen Victoria.
"Patrons included Queen Victoria, the Empress of Germany, the Prince and Princess of Wales, the Empress of Russia and other members of the royal family."
Queen Victoria's royal warrant awarded to Pryce Jones
Newtown historian Mr Pugh said: "There has been concern that crucial documents have been disappearing but it's unclear who took them, when they took them and why.
"This underlines how important it is to have these records in professional hands.
"Over the years people have been allowed access to the records and that may have led to some documents going missing."
David Boardman of Shop Direct added: "It's a bit of mystery where the documents have gone to because Pryce Jones has been bought and sold on by numerous companies over the decades.
"Shop Direct had the documents and we were grateful the council agreed to catalogue the records and store them in a proper environment."
The documents range from the 19th Century to 1970 and were handed to Powys archives by Shop Direct which owns Pryce Jones' former headquarters.
They were also expected to have unveiled its links with most other European royal families.
Mr Pugh said on Friday that there would be some reference to Queen Victoria and Florence Nightingale in the documents.
Sir Pryce Pryce Jones, who founded his Pryce Jones company, went from a shop assistant to a multi-millionaire responsible for 4,000 workers and 250,000 customers.
Sir Pryce was born in Llanllwchaiarn, near Newtown, in 1834, and became an apprentice at the age of 12 to a drapery business in Newtown.
In 1859, he opened his own shop in Newtown and by 1880 he had 250,000 customers all over the world.
As a mark of his success, Pryce Jones was knighted by Queen Victoria in 1887.
He died in 1920 at the age of 85.