Who is Slubgob, the head of the Training College from The Screwtape Letters and what is their importance?

Slubgob is one of Screwtape's favorite targets for contempt, although Screwtape is very gracious at the annual dinner hosted by Slubgob. Slubgob appears as a rather incompetent bureaucrat. He is the principal of the Training College for Young Tempters and does not seem to be doing a very thorough job, even as he churns out graduates.