Jago

An alien being resembling a young male of average build. His spacecraft crash-landed in the south of England forming the crater now known as Hertfordshire. The UK government used advanced psychic weaponry to retcon the public's geographical headcanon and convince people of the county's existence. This is why nobody can name anything in Hertfordshire, even though everybody agrees that it is a real place.

It has been 20 years since Jago landed sir, nobody has visited the area known as Hertfordshire yet.