Made c. 1850 by a cutler in Sheffield, it came for sale at Hansons in Etwall, Derbyshire, on August 15 as part of the 160-lot Brian Jackson collection of weapons and blades.
Matt Crowson, Hansons specialist, said: “Brian’s collection is extraordinary. The penknife, the tip of the iceberg when it comes to fascinating finds, has been in his collection since 1958. The smallest opening penknife recorded in The Guinness Book of Records, owned by Joanne Shaw in Canada in 1999, measured 8mm.
“So, at 7mm the example set for auction is believed to be the smallest of its type in the world.”
Estimated at £100-200, it sold at £320.