H.D. Procter-Gregg was born in England in 1925. He evacuated to Canada in 1940, and was a commissioned Flight Engineer RCAF in 1943-1945. His B.A.Sc. (Aeronautics) from the University of Toronto was obtained in 1949, and M.Sc. (Aerodynamics) from the University of Toronto in 1950. He was with A.V. Roe in Canada from 1950-1959. As an Aerodynamicist, he worked with the development of weapon system performance analysis methods, start-up and management of RCAF data analysis facility in Cold Lake, Alberta. He was manager of international air-to-air missile program in Point Mugu, California.

David came to the United States in 1959 and was naturalized in 1966. He was with Martin-Marietta Aerospace, Denver, Colorado in 1959-1973 as Section Chief Test Planning and Evaluation Titan III Program, Titan III Payload Integration, Manned Space Systems Engineering, including definition of experiment requirements for Skylab and Earth Resources.

H.D. Procter-Gregg married Dolores Bossenberry in 1951 and they have two children, Christine and Robin. He resides in Westminster, Colorado.

In 1973, David co-founded Denver Mineral Exploration Corp., in Colorado, and is responsible for engineering and office management, including definition of computer requirements and hardware selection for remote sensing analysis and development of new algorithms for video processing. He is also responsible for the design and construction of electromagnetic sensing and analysis equipment and testing and calibration program. David develops operating techniques for mineral exploration and is a contributor to digital analysis methods. He serves as corporate secretary and treasurer for DEMEX, and is vice president of engineering for Digital Magnetotelluric Technologies.

David holds patents in telluric instrumentation, and is co-author of an ERDA study of uranium halos as seen by the LANDSAT imagery.