Who is Professor James Blackadder from Possession: A Romance and what is their importance?

Professor James Blackadder is a 54-year-old descendant of Scottish schoolmasters. He looks very gray. He has gray skin and longer gray hair. He usually wears a tweed jacket and corduroy pants. Blackadder does not smile very often. He has been editing Ash's Complete Works since 1951, and he is a discouraging and dedicated scholar. Blackadder became an expert on Randolph Henry Ash out of guilt at a time when Ash was not very popular. He wrote his PhD on Ash and was talked into editing the Complete Poems and Plays in 1959. He thought it was a one-time event, but it has turned into a life calling. Blackadder wonders what his life would be like if he had chosen a different path, but he is genuinely interested in Ash and his work.