Whatever happened to Worthington, and was his
involvement with the boys realistic?
Worthington was introduced to us for the first time in "Terror Castle" as the proper British driver for the Rolls Royce that Jupiter Jones had won in a contest. Robert Arthur used this gimmick very effectively because it showed that good guys do get rewarded every so often, and the idea of having transportation at a moment's notice gave the boys certain freedom in going places.
Arthur realized, however, that he couldn't have the boys being driven around forever in a Rolls Royce without some means to pay for it. In fact, he started laying the groundwork for how to handle that situation in "Terror Castle" where Jupiter alludes to the fact that he's already got plans for what to do when the thirty days run out. He makes reference to these plans again in the early chapters of "Whispering Mummy." Whether he had already decided how to handle it when he wrote these early stories is unknown. However, he eventually wrote the sequence in "Fiery Eye" where the boys recover a ruby for August August, who in turn gives them a generous monetary reward to continue to pay for the use of the Rolls Royce.
Robert Arthur designed the character of Worthington to provide some adult supervision without being too parental of a figure. In fact, even in "Terror Castle," he points out that the boys are his employers, as it were, and he needed to provide them with the same courtesies as he did for his other clients. So it was an ideal situation for the boys. However, Arthur wrote it well, and it was a key element in many of the stories. Worthington used the Rolls for a decoy on several occasions ("Stuttering Parrot," "Fiery Eye"), and he generally tried to be helpful. In a stroke of genius, Arthur even wrote a situation where Worthington wasn't available one time in "Stuttering Parrot," where Fitch is driving the boys. While Fitch is on duty, he is deceived by Mr. Claudius, and this leads to Bob and Pete being kidnapped. Arthur probably figured that we readers would not forgive Worthington if he had made such a mistake that caused the boys to be placed in harm's way; so he created the rather expendable character of Fitch to take the fall for that mistake. He also made Fitch less likable to the boys; so we as the readers do not feel cheated that Fitch never appears in another story.
After Robert Arthur's death, the other writers continued the use of Worthington and the Rolls. However, it became apparent that things were a little different. Mary Carey wrote a scene in "Flaming Footprints" where the boys call Worthington at home so that he can go find out about an address that they had acquired for Demetrieff. While it's true that the boys had a fondness for Worthington, it doesn't seem as likely that he would be going around running errands for them. One of the more unbelievable scenes is in "Smashing Glass" where Worthington agrees to place the Rolls in jeopardy where a window could be smashed. Regardless of his affection for the boys, it would be irresponsible for him to do so and unfair to his true employer.
Neither Arden nor Carey addressed the issue of how the reward given by August back in "Fiery Eye" could continue to fund the boys' use of the Rolls for so many trips when it became clear that the series was going to continue beyond 20 stories in the series. Had Arthur continued to write the stories, I suspect that he would have done something to either make it believable that the boys could continue to use the Rolls (e.g., another client could have continued to fund it, or the boys could have worked out a deal with the car agency, or something), or he would have introduced another mode of transportation.
"Smashing Glass" was the last story in the U.S. in which Worthington played a somewhat major role, although there may have been mention of him in minor situations in the succeeding stories. However, in the German series, a later story in the series revolves around Worthington after he is believed to have died in a mysterious accident.