text: The pants, embroidered with the royal VR monogram, are being sold on behalf of Yesterday's World museum in Sussex.
  Auctioneer Richard Edmonds said: "We've been able to date the pants by measuring the waistband and they are from the last 10 years of her life."
  The sale also includes nightdresses and stockings worn by Britain's longest-serving monarch and Princess Alice.
  The royal intimate apparel - described as in "excellent condition" - is expected to fetch several thousand pounds when it goes under the hammer next week.
  Mr Edmonds, from Chippenham Auction Rooms, said he used the "tried-and-tested method" of measuring the waistline to date the underwear to about 1891.
  "Earlier in her life she was slimmer but her pants got bigger as she got older," he said.
  "As there's such a good photographic record of Queen Victoria, it's possible to calculate her waist measurement over time, so we know roughly when she would have worn items of this size."
  According to Mr Edmonds, the 125-year-old underwear was bought by Yesterday's World museum from a descendant of one of Queen Victoria's ladies-in-waiting.
  "Items of Queen Victoria's clothing were often given to members of the royal household, particularly after her death in 1901," he said.
  "And they're stamped with the royal crest which proves they're from the royal wardrobe."
  Also included in the sale on 11 July are stockings and shoes worn by Queen Victoria's third child Princess Alice and replicas of the Crown Jewels.
  In 2014, a pair of Queen Victoria's silk bloomers sold at auction in Kent for Â£6,200.
target: A pair of Queen Victoria's cotton pants with a 45in (114cm) waistband are to be sold at auction in Wiltshire.