snapmom, 3bay, alcon,
I think the Ferguson in Porter-Ferguson may be William H. Ferguson of Malden, Mass., a Boston suburb. Or more safely put, a lot of things point to that being a strong possibility. He has at least a dozen patents to his name, and all of them are related to auto body repair tools, both hand (e.g., dollies, shrinking dollies) and hydraulic-powered (e.g., spreaders), spanning from 1940 to 1954 or so.
Here's the interesting part - every patent granted to him before 1945 was his own. Every patent in late 1945 and after was granted to him as an assignor to H.K. Porter.
Even more interesting, the earliest instances of "Porter-Ferguson" auto body tools and equipment ("door machines", "hydro-motor tools," etc) that I can find are 1945, all attributed to H.K. Porter in the ads. Nothing shows up before that year.
Earliest instance of "Porter-Ferguson, Inc." that I can find is 1957.
This is TOTAL guesswork, that I have not been able to confirm, but it looks to me like H.K. Porter snatched up auto body repair tools inventor William H. Ferguson, that Porter-Ferguson was at first a brand of H.K. Porter, and later became an entire division of H.K. Porter. And if the presence of his name in the brand and the division is an indication of the value of his compensation package, he did pretty well for himself.
Maybe.
I have no idea how that ties into Trimo-Ferguson, used as a brand name by the Trimont Manufacturing Company from 1930 to 1937. To be used like they used it, as a marketing advantage, it had to be very recognizable name (akin to the Stillson pattern for pipe wrenches) or Trimont gets nothing out of the association. Trimont is also in Massachusetts, so it seems more than just a mere coincidence, almost as if Ferguson switched teams so to speak, jumping from Trimont to H.K. Porter in 1945 after notionally staking out on his own for awhile. But I couldn't find any patents granted to Ferguson before 1940.
Unusually, there's nothing on these tools in DATAMP as far as I can find, and there's no explicit company history of Porter-Ferguson, Inc. (owned by Lowell now) on the Lowell site or in any H.K. Porter histories.
I had to piece it together.