This the the 'Wem Ghost', photographed in 1995 by Tony O'Rahilly while photographing the town hall as it burned in a fire. Apparently it was a real-film rather than a digital photo and while it could be faked using real film, it's very hard to do that without it being spotted. Digital fakery is easy, but apparently this image wasn't digital.
Now, someone claims to have debunked this photo. Brian Lear claims the girl's image appears in a 1922 postcard - the girl at the left of the picture.
Unfortunately these are the only images I have, the ones from the newspaper article I've linked to. I can't enlarge the postcard to see if it's the same girl so I'll take it on trust that the two girls look very similar. They certainly seem to be wearing the same clothes.
I'm not convinced that this is a debunking. I'm not convinced by the original photo either because I'm not aware of any checks made on the negatives. Even so, all I really see here is that the Wem Ghost was dressed in 1920's style and looks like - indeed might have been - the same girl from the Wem postcard printed some 75 years earlier.
There was speculation that the Wem ghost was Jane Churm, who accidentally set fire to an older town hall in the town in 1677. The correlation in dress between the 1920's postcard and the ghost photo suggests it wasn't - but it still does not prove that the ghost photo was faked.
It is possible that the ghost photo contains the image of that girl from the 1920's postcard. She was resident in the same town and we have no record of when she died. It might have been the day after the postcard photo was taken and she might have been haunting the town since then. So the Wem Ghost might indeed be that girl from the postcard.
Or it could have been faked by transposing the postcard image onto the burning town hall. I don't think her stance is the same in the ghost photo as in the postcard but I'd need better images of both to be sure. I also don't think a 1920's postcard photo would reproduce well enough to produce the ghost image. There should be visible grain in the image, and it would be different between the image of the girl (taken with 1920's film) and the image of the fire (taken with 1995 film).
Any competent photo technician could spot that. Hell, with images from 1920 film and 1995 film, anyone with a hand lens should be able to see it.
I'll look out for better quality images on the Internet. The Wem ghost photo won't be hard to find, but the postcard might be.
I'm not saying the ghost photo is real, but I don't believe this debunking is credible. The ghost photo, for me, stays in the 'not disproven' category.
UPDATE - The Shropshire Star is where this story originated. They have an enlarged image of the girl in the postcard and she does look very, very similar to the one in the ghost photo. Even down to the shadow across her face.
The case for 'fake' is very strong indeed for this one.