UFO Spotted Above Mounts Bay?

Highlighted by the dark cloud with its detail obscured, is a bright triangular shape streaking across the sky.

Could it be visitor from space or perhaps an experimental delta-wing aircraft from Culdrose or beyond?

It was snapped by accident and only discovered when Michael Potter reviewed his photographs of Mounts Bay on his computer. He said: 

“I uploaded it to my laptop and decided to delete it because of the apparent sunspot over part of the image.

“Then I noticed on the left hand side of the image something that had not been apparent when I took the photo.

“The photo has not been tampered with or photo-shopped so what is it?”