The prevailing view of history, largely based on propaganda from the Churchill government of the time, is that plucky little Britain was only saved from the clutches of Naziism by the valiant, outnumbered, RAF (with assorted other nationalities thrown in).
Derek Robinson's revisionist history of the invasion scare opens up other areas of investigation, such as the power of the Royal Navy - dwarfing any possible German attack - and the ineptitude of the German running of the war in 1940. While never denigrating the memory of the RAF pilots, he shows very well that had the RAF been wiped from the air in the South East of England in 1940, any invasion fleet would have either been utterly annihilated in the channel or would have landed so few troops that the British Army, despite its desparate shortages, would have been able to contain and destroy them at leisure.
Telling people that there was no threat would not have galvanised the country, so it's entirely understandable that the story of "The Few" became the accepted view for many years.
Robinson is not the first to come up with this alternative point of view, but possibly more well known than others. He also goes slightly overboard with the sarcasm at times for my liking - it is a non-fiction book after all - but is worth 4 stars as an eye opener; an informative and entertaining read.