This is the original hand cut stencil used by Banksy to spray paint the iconic work that was depicted on Blur´s album "Think Tank" from May 2003. It was painted at a scrap yard in Deptford. A photo exists where three different versions can be seen. The version that ended up on the cover is the one to the left and the stencil is the one used to produce the very painting.
This work is not for sale. Similar stencils was shown by Banksy at the Bristol Museum where they hung behind fance. See photos. Another version was painted in Australia at "The Semi Permanent" and a large wooden mural piece. See photo.
All street works are to be considered as "attributed" to. It means to consider as made by the one indicated especially with the strong evidence but in the absence of 100 % conclusive proof. And sold as such. Same goes for barter traded works, gifted works from the artist. Works left behind at sites, in friends apartments in the early years and so on.