The southern and south-eastern perimeter of the airport is also the boundary between Luton Borough and Hertfordshire.
That is not quite true. While part of the county boundary runs along the southern airport fence there is a large chunk of land around Someries that is part of Luton as the county boundary turns south east away from the airport. If measured the other way the land extends to the front of the new terminal.
I wouldn’t get to fixed on county boundary’s as these can be moved. Once upon a time the county boundary ran along the start of the runway at the 26 end. The ILS and airport fence was in Herts but this was changed years ago. If you look at an OS map you can see how the relatively straight line of the border now goes around the airport and not through it.
