'Churchilliana' is a popular collecting niche in its own right, as Britain's wartime Prime Minister Sir Winston Churchill continues to captivate memorabilia collectors around the world.

Now a rare and unseen photograph of Churchill, shown on a horse following his heroic escape from a prison camp during the Boer War, is auctioning in Dorchester, UK, on April 12.

Said auction house expert Andrew Marlborough, as quoted in local newspaper the Dorset Echo: "This could be a major find... Our research so far suggests that this is an unrecorded photo."

The unique photograph dates to 1899, when Churchill was just 26-years-old. It shows him wearing a suit and tie, and wide-brimmed hat. He is surrounded by men of The South African Light Horse Regiment.

The photograph's reverse bears the inscription: "Winston Churchill after Escape".

Winston Churchill after escape - and after 60 miserable hours in 1899

Churchill had journeyed to South Africa the previous year as a newspaper war correspondent, and was captured in November 1899 while riding in an armoured train.

Young Winston was taken to a prison camp in Pretoria, from which he escaped after a month and made his way 300 miles back to safety.

The future British Prime Minister's ordeal included what he later described as "60 hours of misery" as he tried to relocate the British front.

According to reports, the photograph's provenance is also impressive. It has been consigned to the sale by Arthur Knight. Knight was a trained photographer and the son of pioneer diamond miner William Knight.

The unseen Boer War photograph is certainly a great piece of Churchilliana. Other good buys are those directly linked to Churchill himself.

This historic Winston Churchill autographed handwritten letter helped lose him his seat as an MP in Oldham - we have it for sale here

Examples we've handled here at Paul Fraser Collectibles include this Winston Churchill autographed and handwritten letter. We have the rare manuscript for sale here.

Dated 7 January 1904, it was because of this very letter that the Oldham Conservative Association, as written in a later piece of correspondence, "forfeited their confidence in him as member for Oldham."

Following his deselection in the seat of Oldham, Churchill was invited to stand for Manchester North West. He later became Prime Minister on 10 May 1940.

The rest is history, and Sir Winston Churchill's collectibility remains perennial. Watch this space for more news on the Dorset auction.