I ran into the web site for the Screen Actors Guild the other day & low and behold, a page for Bob. Not a whole lot of background, but I loved this blurb:
"A leading star at MGM -- signed in 1929 when he was 25 -- tall, debonair, recognized as one of the best-dressed men in Hollywood, "Bob" wielded considerable clout, and did not hesitate to use it. As Colliers magazine once put it: "Nobody Pushes Bob Around."
Go check out the site. I wish they had larger versions of the photos they have on the page.