A new digital library of aerial photos of UK
One of the bigger charities in Britain is English Heritage and they are putting together an archive of historic aerial photos. At the mo the site seems to be under heavy load due to some publicity on the BBC news site but I thought Id post here to see what it becomes in the future. It seems to mainly target older images such as those during the war or old black and white stuff. Its supposed to go up to about 2006 tho...
These dont seem to be ortho photos like satellite so you might have to use them as resources, textures, or somehow transform them to square them up for a top down view. But since getting any kind of aerial photo is hard graft then this could be a good site: