The personal collection of the late Mary Soames (1922-2014), the last surviving child of Sir Winston Churchill, has been consigned to Sotheby's in a landmark sale.

Winston Churchill and Mary together outside the Mansion House in London

The auction, to be held on December 17 in London, celebrates Soames' life as well as her father's, with the young girl becoming a close confidant of the prime minister during the war years.

"Mary Soames was an eyewitness to some of the most important moments in our recent history," said Prime Minister David Cameron of Lady Soames in May 2014.

With Churchill a keen painter, some of the biggest draws in the sale will undoubtedly be his artworks, which mainly depict his famous Chartwell home or his birthplace of Blenheim Palace.

The Goldfish Pool at Chartwell - the record for Churchill's art stands at ?�1m, after Chartwell Landscape with Sheep sold at Sotheby's in 2007

The Goldfish Pool at Chartwell, an oil on canvas from 1932, will sell with a ?�400,000-600,000 ($643,280-$946,920) estimate.

A further group of paintings by what Churchill called "real painters" will also feature, with the highest estimate held by Oswald Birley's 1951 portrait of Churchill in a siren suit at ?�100,000-150,000 ($160,820-241,230).

Of the items personally owned by Winston Churchill, his red morocco leather dispatch box is the most desirable, with the lid stamped "THE RT HON WINSTON CHURCHILL., MP SECRETARY OF STATE FOR THE COLONIES". It is expected to see between ?�5,000 and ?�7,000 ($8,041-11,257).

Battered and bruised, the dispatch box is nonetheless a great item from Churchill's time as secretary of state for the colonies

Soames' personal items are a reflection of the famous names she came into contact with both at Chartwell and on family visits. These include a signed photograph of US president Franklin D Roosevelt, which is inscribed "For Mary/from her friend the other naval person Franklin D Roosevelt".

Signed in 1943, the piece dates from a trip to the USA with her parents, after which she wrote in her diary: "I still the Pres. magnetic and full of charm, his sweetness to me is something I shall always remember."

It will sell for ?�2,500-3,500 ($4,020-5,628).

Paul Fraser Collectibles has a superb collection of Winston Churchill memorabilia for sale.