This 'Harry Potter' word somehow found its way into British politics

It seems that our foreign secretary hasn't properly done his research about Harry Potter. 
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In a bid to discredit Labour leader Jeremy Corbyn ahead of snap elections next month, the well-spoken Boris Johnson called Corbyn a "mutton-headed mugwump":Excl: Boris Johnson tells voters not to be tricked into feeling sorry for “mutton-headed old mugwump” Jeremy Corbyn; https://t.co/P3aziC2YM