Using AOS's artwork
A similar post has been made though there wasn't really a clear answer to the question.
I'm looking to use one of the great man's works on the cover of a musical output I have made which was strongly influenced by the piece of art in question along with the ninth arch.
If anyone has information on the copywrites or who I would need to speak with in regards to this I would be very thankful.
Besides Mr Staley here I wouldn't be surprised if Mr Semple or his colleagues at Fulgur knew:
It's my understanding that there is no identifiable copyright owner. Probably best if you assign copyright to "The Estate of Austin Osman Spare".