A good starting point would be Sir Arnold Plant and his 1934 paper  
titled, "The Economic Theory Concerning Patents for Inventions," in  
Selected Economic Essays and Addresses (London: Routledge & Kegan  
Paul, 1974).  
Ronald Coase, a student of Plant at the LSE in the early 30s, has  
written about him in the New Palgrave, and also in "The unfinished  
agenda" (London, Institute of Economic Affairs, 1986). 
 
Carlos Rodr=EDguez Braun