A mitten worn by British Everest expedition leader Sir John Hunt at 27,400 feet in May 1953 has been discovered in a shoebox.

A client drove from Wales to bring the historical treasure for valuation at Hansons Auctioneers' Staffordshire saleroom Bishton Hall - much to the amazement of valuer Jim Spencer.

He said: "Sometimes a client walks in with an old carrier bag or shoebox and you just sense a surprise coming, something worthy of a gasp. This was a case in point. Seeing that humble old mitten was a catch-your-breath moment. It was used during the first successful ascent of Mount Everest.

"Holding it seemed to transport me to a higher altitude. It's a real piece of history worthy of being displayed in a museum cabinet, so it would be lovely if an institution or gregarious collector were to win the auction and exhibit the object for all to enjoy."

The mitt will be offered for sale with a guide price of £2,000-£3,000 on 10 May.

It comes with a hand-written and signed note of provenance from Hunt, which states: "Dear Mr Jenkins, Thank you for your letter dated 17th September. I hope that the enclosed down mitt, used by me at 27,400 feet on Everest on 26th May 1953, may be helpful to you in your campaign."

Hunt chose two pairs of climbers to make the final push for the summit. The first pair, Tom Bourdillon and Charles Evans, came within 330ft on 26 May but turned back after running into oxygen problems. The same day, Hunt, ascending with Sherpa Da Namgyal, intended to reach 27,900 feet to leave equipment for the second summit party of Edmund Hillary and Tenzing Norgay. The pair came to Hunt's rescue when he could not move anymore.