The tree was located about 30 miles from the northern border of England. It could possibly be described as on the middle by longitude but it's far from the middle of England as a whole.
No need to downvote me stickler!
I don’t normally say anything but thanks when corrected but in this case most foreigners would expect England to represent the GB landmass so in this case there’s no need to point out the error. Even if it was , it’s odd to start explaining the borders, it’s almost as if you are entirely confused by the prospect of the tree being in the center of the GB landmass. I’m sure you are not but that’s what it comes across as. Only saying this so you work on your context analysis in discussions.
I would say it is worth pointing out though, specifically because foreigners are most likely to be confused between England and GB. Hope you get your karma back :)