Both projects advertise their CC-by-sa credentials and, both projects inform the world that their material is available for use in Wikipedia. The British images can be found on Commons, and the German images as well.
|© Copyright Hansjörg Lipp and licensed for reuse under this Creative Commons Licence.|
All the Geograph pictures come with geo-tagging. They are another large collection that provides provenance to this type of data.. Another example that the existing absolute lack of discussion with OpenStreetMap is plain silly.