Rich Walker is currently the Director of Technical Training for GUE. I have had the pleasure of meeting him a couple of times when I was diving in Malta, however I have never dived with him myself. He exclusively teaches GUE courses, so you won’t get a PADI Open Water certification from him.
Rich has a company called Wreck and Cave. Here he lists all the courses that he can teach and the dates of the upcoming courses.
However, this is not why I am writing about him. I recently signed up for his newsletter and I have to say that there are some fantastic articles inside it. I won’t reprint them here, as I doubt I would have permission to do so but if you are interested in advancing your diving knowledge then you should sign up for the newsletter here. He recently wrote an instructional guide for setting up stages for decompression dives, definitely worth the read.
I hoping that someday soon (probably in 2015) I will do a GUE Fundies course with him aiming to getting a Tec pass.