On 3 September 1939, Neville Chamberlain, Prime Minister of the United Kingdom, reconstructed his existing government so as to be suited for the Second World War. The most dramatic change to the ministerial line-up saw the return of Winston Churchill as First Lord of the Admiralty. Other changes included Lord Caldecote replacing Lord Maugham as Lord Chancellor, Sir John Anderson replacing Sir Samuel Hoare as Home Secretary (Hoare became Lord Privy Seal with a wide-ranging brief) and the return of Anthony Eden to the government as Secretary of State for Dominion Affairs. However, the administration was not a true national unity government as it was made up primarily of Conservatives with support from some National Labour and National Liberal members. There were no representatives from the Labour Party or Liberal Party^[1]

The government was notable for having a small war cabinet consisting of only the principal and service ministers, with most other government positions serving outside the Cabinet. The War Cabinet included Chamberlain, Hoare, Chancellor of the Exchequer Sir John Simon, Foreign Secretary Lord Halifax, Churchill, Secretary of State for Air Sir Kingsley Wood, Minister for Coordination of Defence Lord Chatfield, Lord Hankey (as Minister without Portfolio), and Secretary of State for War Leslie Hore-Belisha. Oliver Stanley replaced Hore-Belisha in January 1940 while Chatfield left the war cabinet in April 1940.

The government ended on 10 May 1940 when Chamberlain resigned and was succeeded by Churchill who formed the War Coalition.

Upon the outbreak of the war, Chamberlain carried out a fullscale reconstruction of the government and introduced a small War Cabinet who were as follows:

• Neville Chamberlain – Prime Minister and Leader of the House of Commons
• Sir Samuel Hoare – Lord Privy Seal
• Sir John Simon – Chancellor of the Exchequer
• Lord Halifax – Secretary of State for Foreign Affairs
• Leslie Hore-Belisha – Secretary of State for War
• Sir Kingsley Wood – Secretary of State for Air
• Winston Churchill – First Lord of the Admiralty
• Lord Chatfield – Minister for Coordination of Defence
• Lord Hankey – Minister without Portfolio

• January 1940 – Oliver Stanley succeeds Leslie Hore-Belisha as Secretary of State for War.
• April 1940 – Hoare swaps Lord Privy Seal with Wood for Secretary of State for Air. Lord Chatfield leaves the government and the office of Minister for Coordination of Defence is abolished.

• Thomas Inskip, 1st Viscount Caldecote – Lord Chancellor
• James Stanhope, 7th Earl Stanhope – Lord President of the Council and Leader of the House of Lords
• Sir John Anderson – Secretary of State for the Home Department
• Malcolm MacDonald – Secretary of State for the Colonies
• Anthony Eden – Secretary of State for Dominion Affairs
• Lawrence Dundas, 2nd Marquess of Zetland – Secretary of State for India and Burma
• John Colville – Secretary of State for Scotland
• Oliver Stanley – President of the Board of Trade
• Herbrand Sackville, 9th Earl De La Warr – President of the Board of Education
• Sir Reginald Dorman-Smith – Minister of Agriculture
• Ernest Brown – Minister of Labour and National Service
• Walter Elliot – Minister of Health
• Euan Wallace – Minister of Transport
• Leslie Burgin – Minister of Supply
• William Shepherd Morrison – Minister of Food and Chancellor of the Duchy of Lancaster
• Herwald Ramsbotham – First Commissioner of Works
• Hugh Macmillan, Baron Macmillan – Minister of Information
• Ronald Cross – Minister of Economic Warfare
• Sir Walter Womersley – Minister of Pensions
• George Tryon – Postmaster General
• Edward Turnour, 6th Earl Winterton – Paymaster General
• Sir Donald Somervell – Attorney General
• Sir Terence O'Connor – Solicitor General
• David Margesson – Chief Whip

• October 1939 – The position of Minister of Shipping is created, with Sir John Gilmour the first holder.
• November 1939 – Lord Winterton resigns as Paymaster General and no successor is appointed.
• January 1940 – Oliver Stanley becomes Secretary of State for War and a member of the War Cabinet in succession to Leslie Hore-Belisha (resigned) (see above) and is succeeded as President of the Board of Trade by Andrew Duncan. Lord Macmillan resigns as Minister of Information and is succeeded by Sir John Reith.
• April 1940 – Robert Hudson succeeds Sir John Gilmour (deceased) as Minister of Shipping. Lord De La Warr exchanges President of the Board of Education with Herwald Ramsbotham for First Commissioner of Works. William Shepherd Morrison swaps the Chancellor of the Duchy of Lancaster for the Postmaster General with George Tryon and is succeeded as Minister of Food by Lord Woolton.
• May 1940 – Sir Terence O'Connor dies and no new Solicitor General is appointed before the government falls.

Members of the Cabinet are in bold face.

• D. Butler and G. Butler, Twentieth Century British Political Facts 1900–2000.