How Long Was The Battle of Britain Expected to Last?

[Bobb4]

Originally Posted by senseispcc

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So the duration of the battle of Britain is very vague because German did really never end it officially!

The moment they (Germany) went defensive the Battle of Britain was over.
Speaking of battle, it is highly likely the individual pilots would have a sense of an endless struggle. The only comparison they had was WW1 and the channel was one big nomansland, so it is easy to imagine some pilots belief that it would last for ten years as conjected by the OP.
But i seriously doubt it was a universally held opinion.