Roger (Gilbert) Lancelyn Green was a British biographer and children's writer. He was an Oxford academic who formed part of the Inklings literary discussion group along with C.S. Lewis and J.R.R. Tolkien. Born in 1918 in Norwich, England, Green studied under C. S. Lewis at Merton College, Oxford, where he obtained a B.Litt. degree. He delivered the 1968 Andrew Lang lecture. Green lived in Cheshire, in a manor which his ancestors owned for over 900 years. He died in October 1987. His son was the writer Richard Lancelyn Green
Probably best to read as a resource while reading/studying the plays themselves, but since I had a library copy I read it straight through. That gave me a good overview of the plots of the plays, but I'll need to buy a copy for future use.