In Britain the story (and the audio) of the events of 3rd September 1939 are so well known and Neville Chamberlain's moving broadcast so cherished that the it's strange that the French declaration of war some hours later is so often relegated to a footnote.
The schoolboy histories that I grew up with typically manage to imply that the timing of the French declaration speaks both of their junior role in the Anglo-French alliance and their reluctance to prosecute the war (of a piece with their collapse less than a year later).
It seems unlikely those British histories are doing much more than point scoring with the benefit of hindsight so what is the true story behind the French delay? Was there a technical reason? Was France really the junior partner, unable to move first? Why didn't the two allies ensure their declarations of war were timed together?