Checking originality of concept

Hey guys, I'm starting up a piece of fiction here, but before I get deep into it I need to make sure I'm not ripping off someone I've never heard of.  So has there ever been a novel based around the essential concept that the American Revolution failed, and that England controls the USA even today?

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If the section of land known as the continent of Europe never existed, then chances are all the land-masses would look much different as well, and possibly be situated much differently in relation to what they look like in real life. That would also have to be factored in to an extent.