Winston Churchill

Clemmie

King George VI

Elizabeth Layton

Neville Chamberlain

Viscount Halifax

Sir John Simon

Sir Anthony Eden

Clement Atlee

General Ismay

General Ironside

Arthur Greenwood

Sir Samuel Hoare

John Evans

Air Chief Marshal Dowding

Admiral Ramsay

Admiral Dudley Pound

President Roosevelt (voice)

Tom Leonard

Sawyers

Cabinet Secretary Bridges

Randolph Churchill

Diana Churchill

Mary Churchill

Sarah Churchill

Pamela Churchill

Lord Stanhope

Lord Kingsley Wood

Lord Londonderry

House of Commons Speaker

Ernle Hastings

Equerry

Reynaud

Daladier

BBC Producer

Actor

Abigail Walker

Alice Simpson

Marcus Peters

Maurice Baker

Jessie Sutton

Young Girl on Tube

Agnes Dillon

Oliver Wilson

Margaret Jerome

Brigadier Nicholson

Ramsay Staffer

Reporter

Teenage Girl at Tube Map

Naval Map-Room Officer

Sybil

Sir Alexander Cadogan

AD Nicholl (Secretary #1)

W D Wilkinson (Secretary #2)

Christopher Wilson (Photographer)

Maid

Cook

Back Bencher

Cecil Beaton

Member of Parliament (uncredited)