The photographer mentioned was Russ Spalding and yes, he had a Darrin with quite a few modifications done to it. The frame on his car had an additional "X" member added to test rigidity, to name one I could think of right away. I was a guest of his many years ago at his home in Colorado Springs and we spent an afternoon going thru his personal papers from KF. He gave me several photographs he took while employed at KF, as well as a few bits and pieces I needed for the first Darrin I owned at the time.
Russ was not the only company photographer, but he was part of the team when the 1951 cars were introduced. He told me of being in charge of getting the models to the shoot sites and one time, while taking one to a site north of the factory, the young lady was changing outfits in the back seat. He said he almost ran off the road staring into the rear view mirror rather than paying attention to the road.
He also said that quite a few of the people in the pictures were employees or family of employees. One shot of a family gathered around a Traveler was comprised of an employee and her family. Many of the pictures were taken near the factory in an area that had a park-like setting. Today, it's a subdivision full of tract homes.
Russ passed away several years ago.