Although it looks pretty yellow here, in flight it looked white, with black borders. I couldn't get an open-wing shot, but hoped the backlit shot might help. Taken around 9am this morning near Cambridge, so from the location alone, I guess that pretty much assures it's CY not Pale CY?
![Image](http://www.pbase.com/dilettante/image/156801733/original.jpg)
![Image](http://www.pbase.com/dilettante/image/156801732/original.jpg)
There was also at least one, maybe up to three, 'classic' yellow CYs there.