UFO Sighting in Tintagel, England on 1998-08-31 14:30:00 - I took this photo from tintagel castle of gulland rock and trevose head cornwall

In 1998 i took this photo. in 2013 i had another look at it with the idea of putting in a comp. i made it lighter and was supersized to see this sphere in the top left hand corner. this did not show up in the original photo which was darker. it looks like a black hole. the photo was taken with a minolta srt 101 film camera with a rokkor 4.5 300mm lens. it was taken in september late afternoon. it was raining at the time. the neg was checked in jessops photo shop,and the sphere is on the neg. i wonder if you have any idea as to what it might be?