This card dates from the dedication of the British tomb.
Pictured at left of the interior is the Cenotaph (commemorating the war dead but containing no body) in Whitehall by Sir Edwin Luytens, dedicated on the same occasion. It replaced a temporary structure that he had designed for the Victory (Peace) Parade in 1919. The Poetry Library lists the poem among its "lost quotations," whose source remains to be identified.
The anniversary of the end of the war, originally called Armistice Day, became Remembrance Day (the closest Sunday to November 12; since 1945) in the Commonwealth and Veterans Day (1954) in the US.