Question about color vs. b&w

If we can believe the contributor(s) to Wikipedia in the link below, two first season episodes were shot in color (at least partially in the case of "The Four-Steps Affair") because it was intended that footage would end up in theatrical features. I think the pilot was probably shot in color due to foresight that the series would be picked up and at some point turn over to color if not initially. When the series was underway the decision was probably made to film some footage in color for the features, perhaps just as Goldfinger was about to released and when ratings were picking up.

Season One was filmed entirely in black and white, except for the pilot episode, "The Vulcan Affair," and "The Double Affair," which were filmed in color since they were planned to be turned into feature films. Additional scenes filmed later, in the case of "Vulcan," and in the case of "Double," concurrently . (The portions of "The 4 Steps Affair" which included the expanded scenes from both feature films had been filmed in color even though all Season One episodes were broadcast in black & white).

http://en.wikipedia.org/wiki/List_of_The_Man_from_U.N.C.L.E._episodes