A gun used by Sir Winston Churchill in an escape during the Boer War is to go on sale at a Sussex auction rooms.

The revolver will be among other items of Churchill memorabilia sold by specialist auctioneers Wallis & Wallis in Lewes on May 1.

The story says the young Churchill was serving in the 4th Hussars and working as a war correspondent for the Morning Post in South Africa during the Boer War in 1899, when he borrowed the gun from a British homesteader.

He was travelling on an armoured train when it was attacked and seriously damaged by Boers and many of his comrades were killed.

Churchill and some of the surviving soldiers managed to get the stricken train going again but when he went looking for some of the missing officers he was captured.

He escaped from the Boers by overpowering his guard and went on the run.

Exhausted and desperate, he knocked on the door of a homestead to find it was occupied by an Englishman called John Howard.

After resting awhile, he set off with a basket of food and a six-shot pinfire revolver borrowed from Howard, sneaked on to a train, hid under a tarpaulin and escaped over the border.

Two years later, in 1901, he returned the revolver to his benefactor along with a thank you gift of a glass brandy flask and fitted silver cup which he had engraved with John Howard's monogram and an inscription.

All three were presented to John Howard in a black metal box bearing the inscription "Returned to friends at Witbank from WS Churchill 1901".

The revolver and flask were inherited by John Howard's grandson, KG Howard, a warrant officer in 17 Squadron of the South African Air Force during the Second World War.

When he was killed in action, it passed to 17 squadron's benevolent section and then to the present vendor's aunt.

Roy Butler, senior partner at Wallis & Wallis said: "I think this is a thing of national or even international importance. Churchill's mother was American and the Americans love anything to do with him.

"The gun is a rare item, a historical item, with a fascinating story attached to it.

"My first instincts were this could be worth £5,000 to £10,000 but then I thought about its national importance. Our estimate now is it will reach between £10,000 and £15,000.

"There are so many people who are interested in Churchill, including collectors and institutions. Maybe the Imperial War Museum might be interested."

The gun, flask, cup and box will be available for viewing at the Arms Fair at the London National Hotel on April 26 and 27 or at the sale room in West Street, Lewes, from 9am until 10.30am on the morning of the sale. Bidding starts at 11am.