The Political Root
Of
Road Accidents
by
Lieut. Col. Mervyn O'Gorman, CB
Member of the Inst. of Civil Engineers
Member of the Inst. of Automobile Engineers
Member of the Inst. of Mechanical Engineers
Vice-Prest. of the Internat. Assoc. of R. Automobile Clubs
The Root Of Road Accidents
http://library-2.lse.ac.uk/collections/pamphlets/document_service/HE3/00000080/doc.pdf
One interesting thing I'd not heard before:
There had been a steady rise in total fatalities from 1926 (the earliest I have figures for) to 1930, and then the trend reversed and there was a steady fall to the end of the 40's if you ignore the blackout years.
Apparently they scrapped the general 20mph limit in 1930!