Black August

Written in the early thirties, published in 1935, during the great depression. Set in England it was written during the reign of King George the fifth and before the abdication crises of his successor, Edward the eigth. This is relevant because it portrays the then crown prince as a popular choice as a unifying regent after the collapse of a normal society post 1935.
The chief character is one of Wheatleys "gung ho" enlish heroes. and is a good read if you put yourself, not as the main character, but as one of the affected and how one would cope oneself in such a situation. No law and small groups out to survive.
Good escapist page turner if you can stomach the class society of the 'tween war years.