Harold Lamb is a medical doctor and one of the protagonists of the Utgarda Trilogy. From The Old Man’s Request: Book One of the Utgarda Trilogy, we learn that:

“Dr. Lamb had just completed his residency at Reister University Hospital and was teaching Basic Anatomy to first year medical students.”

Excerpt From: Stieglitz, Joab. “The Old Man’s Request: Book One of the Utgarda Trilogy.” Lulu.com, 2016-12-01. iBooks.

Doctor Lamb is a scientist and inventor of an irrigation device for the eyes. He is also a country boy from an affluent family, who aside from his experiences in the Great War, has lived a fairly sheltered life in the country. Harry is a pragmatist and a realist. He firmly believes in the notion that what he can see, feel, and touch actually exists. Anything else is a product of imagination or delusion.

Doctor Harold Lamb was another player character from a Call of Cthulhu RPG campaign that I ran in the 1990’s.  Harold Lamb was very much the rationalist and intellectual portrayed in the Utgarda Trilogy.