Do you know what this strange line is?

These two pictures show a strange dark line that was visible around the time of maximum eclipse at Waresley Park Garden Centre. Chris Thorne took the photos and says that several other witnesses saw the line as well (so we don't think it's an out-of-focus washing line).

According to Chris the line appeared curved a short time later and seemed to bend horizontally as well as vertically. He compared it to a dark rainbow but there was no colour to it as you can see from the photos. Maximum eclipse at Waresley was around 94% obscuration.

Click on the picture for a bigger version.

P.S. It now seems likely that these were shadows cast by aircraft vapour trails. The Sun's large diameter usually makes these shadows too diffuse to see but the Sun in eclipse will have caused sharper shadows.