The collection chiefly compiles Lady Onslow's personal letters written to her parents and sister "Jim" from her travels in Churchill's service. They provide first hand evidence of her experiences and include lively recollections of Churchill, descriptions of her work and colleagues, and descriptions of journeys, accommodation and surroundings. The letters are supplemented by a small number of photographs and other mementos.

The material held at Churchill Archives Centre mainly consists of Colville's diaries. They provide an insight into the decision-making of three Prime Ministers and the meetings held with other top officials, as well as the lives of key figures during World War II, and its aftermath.

"Before I forget", annotated draft of Hughes-Hallett's memoir on Combined Operations, 1941-5, including his memoir of the Dieppe Raid and the planning for D-Day (Operation Overlord); with a letter to him from Winston Churchill MP (Prime Minister), 19 September 1954

Colour film reel shot by Courtenay, mainly from his experiences in the Second World War, including footage of Winston Churchill in Canada and giving the "Iron Curtain" speech, 1946, and footage of American forces in the Pacific.

Telegram from General Sir Archibald Wavell [Supreme Commander, South West Pacific] to WSC regarding military command in Burma [later Myanmar]: feels disturbed at the "lack of real fighting spirit" shown by troops in Malaya [later Malaysia] and Burma, and lists some causes; comments on Lieutenant-General Thomas Hutton [General Officer Commanding, Burma] and proposal to replace him with General Harold Alexander; refers to own rapid recovery.

Telegram from WSC to General Sir Claude Auchinleck [Commander in Chief Middle East] marked "personal and secret" informing him of his intention to announce Auchinleck's assumption of command [ of Eighth Army] during his speech in the vote of censure debate on Thursday [2 July].

Telegram from WSC to General Sir Claude Auchinleck [Commander in Chief Middle East] marked "personal and secret" informing him that he will now be announcing his assumption of command [of Eighth Army] in the House of Commons tomorrow.

Telegram from WSC to the British Ambassador in Egypt [Sir Miles Lampson, later Lord Killearn] marked "personal and private" asking him to see his "young friend" Captain Frederick William Deakin who helped him with the Marlborough biography and is now in Egypt on Special Operations Executive work.

Telegram from WSC [Moscow, Soviet Union] to Deputy Prime Minister [Clement Attlee] reciting text of message from Averell Harriman [Special Representative of President Roosevelt with the rank of Minister] to Stalin replying to the Soviet memorandum of 13 Aug and reaffirming WSC's statement that no promise has been broken regarding the Second Front Annotated. Those annotations in red ink may have been added at the time of the writing of WSC's "The Second World War" in the period c1948-1954.

Telegram from WSC [Cairo, Egypt] to General Hastings Ismay [Chief of Staff to the Minister of Defence] marked "most secret and personal" asking for reports on developments in the Solomon Islands and on U-Boat sinkings Annotated, probably during writing of WSC's "The Second World War" c1948-1954.

Telegram from WSC [Cairo, Egypt] to Deputy Prime Minister [Clement Attlee], Foreign Secretary [Anthony Eden, later Lord Avon], General Hastings Ismay [Chief of Staff to the Minister of Defence] and the Chief of the Air Staff [Air Chief Marshal Sir Charles Portal] regarding the long-term policy of placing an Anglo-American air force on the Russian southern flank in the Caucasus Annotated, probably during writing of WSC's "The Second World War" c1948-1954.

Telegram from WSC [Cairo, Egypt] to the Chief of the Air Staff [Air Chief Marshal Sir Charles Portal] marked "most secret and personal" regarding heavy night bombing raids on Berlin [Germany] Annotated, probably during writing of WSC's "The Second World War" c1948-1954.

Telegram from WSC [Cairo, Egypt] to General Hastings Ismay [Chief of Staff to the Minister of Defence] marked "most secret and personal" suggesting that it would be wise to describe "Jubilee" [Codename for raid on Dieppe, France] as a "Reconnaissance in force." Annotated, probably during writing of WSC's "The Second World War" c1948-1954.

Telegram from WSC [Cairo, Egypt] to First Sea Lord [Admiral Dudley Pound] marked "most secret and personal" asking him to cable the latest news of the progress of the ships carrying the Sherman tanks Annotated, probably during writing of WSC's "The Second World War" c1948-1954.

Letter from Philip Allen [Assistant Private Secretary to the Minister of Home Security] to Kathleen Hill [Secretary to WSC], confirming that a second Anderson Shelter had been sent to Chartwell [Kent].

Letter from Philip Allen [Assistant Private Secretary to the Minister of Home Security], to Kathleen Hill [Secretary to WSC], confirming that an Anderson Shelter big enough to accommodate 10 people had been despatched to Chartwell [Kent], at a cost of 11l 15s.

Letter from Mary Shearburn [Secretary to WSC, later Mary Thompson] to Philip Allen [Assistant Private Secretary to the Minister of Home Security], requesting an Anderson Shelter to fit 10 people to be delivered to Chartwell [Kent]. [Carbon].

Note from Mary Shearburn [Secretary to WSC, later Mary Thompson] to WSC, confirming that although construction of Anderson Shelters had ceased, there were a few available, at 10 pounds for a six seater, and 15 pounds for one accommodating up to 10 people [annotated by WSC, asking her to buy a large shelter for Chartwell, Kent].

Note from Mary Shearburn [Secretary to WSC, later Mary Thompson] to WSC, on air raid precautions at Chartwell [Kent], noting that there were adequate shelters for the staff and the cottages, that for anyone sleeping in the "big house" there was a cellar which would make a splendid shelter, leading out of the day nursery, and that if an Anderson Shelter were required for CSC when staying in the new cottage, a good place for it would be opposite the door to the muniment room.

Minute from Leslie Rowan [Private Secretary to WSC] to WSC, on the ration of sugar for the bees at Chartwell [Kent].