A Polish skywatcher living in the UK accidentally captured an image of a strange object while photographing birds in Corby [Northamptonshire] on 14th January 2007 at about 15:05.
He didn't notice the object itself or anything that could be responsible for this image [for example kites].
The rectangular unidentified appeared only on one photo from the series, taken using a Samsung i6 camera.
Source & References:
NPN - http://www.npn.ehost.pl/ - 26/01/07
NOL - the Eastern European UFO Journal", 12/02/07