The military controlled the press
No it did not.

This is my only case.
1: That Britain had no choice but to resist the German onslaught;
2: That the British people overwhelmingly understood and accepted that;
3: That the army was well led.

Jim himself acknowledges that "there was a necessity to fight."
That endorses 1 and 2.

Military historians are unanimous about 3, so who cares for the opinion of ignorant, unread people like Jim?