A rifle belonging to a adventurer described by US president Theodore Roosevelt as the “last of the mighty hunters” will go on sale later this year.

Frederick Selous became famous in his own lifetime for his expeditions in the African bush between 1870 and 1907.

The Selous Collection at the Natural History Museum in London features 524 mammals shot by him on three continents.

Patrick Hawes, Bonhams sporting gun specialist, said: “This is an absolute must for anyone who loves that period of African history, and who reveres the memory of Selous.

“He lived at a time when swashbuckling white hunters were king of the African bush and took an American president, Hollywood stars and crowned princes on safari to shoot game animals which then numbered in the millions.”

The firearm is a rare .256 falling-block rifle by Holland & Holland with an estimated selling price of £5,000 to £7,000.