Doctor Who season 3 questions

BBC America is running a Doctor Who marathon and I caught a show I hadn’t seen before (I was never a very faithful fan, most of the shows I have watched have been in these marathons). This is the one with Mark Gattis as Lazarus/Scorpion man.

In the episode, a strange young man warns Mrs. Smith (Martha’s mother) twice about the Doctor and how he is dangerous. At one point Mrs. Smith says his name, but I couldn’t catch it*. In the IMDB credits he is listed as “mysterious man” (if I am looking at the right role in the credits) and that actor only appeared in Doctor Who in this one episode.

Was this ever followed up on in later episodes? It was so pointed and specific that I didn’t think this could be a throwaway. *One IMDB review says that this episode continues a “Mr. Saxon arc” but the only character named Saxon I could find in the whole series is Lucy Saxon. Is there a Mr. Saxon arc, and what was it about?

Also: early in the episode, Lazarus says to the old lady something like “our friend will get his money’s worth,” so I thought there was going to be a mysterious backer of the experiment/project that would turn out to be the real villain. Any connection to the above?

“Harold Saxon” was the name that the Master used when he was running for Prime Minister - and as part of his plot, it makes sense for him to be interfering with the Doctor’s relationship with Martha, by warning off Martha’s mother.

Oh, ok, I had forgotten that name (I have seen the Master as PM episode(s)). Also fooled because this actor wasn’t the same as the actor who played him as PM.

Any chance he is also the person referred to who was apparently some kind of financial backer for the Lazarus project?

He was, yes.

I think the “mysterious man” was supposed to be an agent of Saxon’s, not Saxon himself (the Master has people for that sort of thing).

Was that revealed in the episode? I missed the first 5 minutes or so.

Been a while, but IIRC, it wasn’t relevant to the episode itself, but to building the Mr Saxon arc - establishing Saxon as a man of influence and having him arrange things to interfere with the Doctor and Martha.

The Master ended up using the Lazarus project to rapidly age the Doctor.