One who is not British(from birth in Great Britain, not necessarily of British descent) that is obsessed with all forms of media and culture from Great Britain, despite having no connection to the country itself. These
people are typically American, but can be from anywhere. They
will usually be seen watching shows like Doctor Who, Sherlock Holmes, etc, and
will often attempt to use British idioms, fake a British accent, and pretend to know about British culture. British equivalent to Weaboo and Westaboo.
I know this one Britainophile that's
obsessed with Doctor Who and often pretends to go traveling through time and
space in that
grimy phone booth he calls a Tardis.