The question isn't about what would have happened in that event. It is: Have one or more recognized historians delved into this question (of what would have happened if Britain had surrendered to or collaborated with Germany under another leader than Churchill)? What were the findings of their inquiries?

(In "The Rise and Fall of the Third Reich," William L. Shirer hypothesizes that the relationship between occupier and occupied would have been a hostile one, but doesn't go into what the implications would have been for war itself.)