As a character in one of those dull governmental Holmes cases, "The Adventure of the Bruce-Partington Plans," Sir James isn't someone to whom I've paid a lot of attention to in my studies of the Sherlockian Canon. He actually dies just before Holmes and Watson can meet him, and not because he's a murder victim. He basically dies of embarrassment. Or shock. Or failure. Citizens of the Victorian era seemed to be so fragile that emotions caused them to fall faint or completely give up the ghost, and Sir James Walter was one of them.
But here's the interesting thing about Sir James. He is first explained to us as "a government expert." Later we learn that he's "a scientist" and "the head of the Submarine Department," but all in all, he's one of those brilliant minds that governments used to keep on their payroll before the private sector started stealing them away. Sort of like Mycroft Holmes.
Sir James Walter also had one more similarity to Mycroft Holmes: a younger brother who disdained to take up government service. It is perhaps this reason that Sherlock Holmes doesn't suspect Colonel Valentine Walter, and even admits to being surprised to find he's the culprit. Sherlock probably saw Valentine as a sort of kindred spirit that way. When Sherlock says of Valentine, "How an English gentleman could behave in such a manner is beyond my comprehension," it becomes even more clear that he sees the younger Walter as a peer of sorts.
It is interesting to note that while we have no evidence of a direct working relationship between Mycroft Holmes and Sir James Walter, in the movie The Private Life of Sherlock Holmes, Mycroft is the one we find involved with Her Majesty's secret submarine program, rather than Sir James.
But even though we would expect the massive Mycroft to fall prey to a massive heart attack, he does seem to be a little sturdier than the late Sir James.
In any case, it will be interesting to see what this week brings in the ongoing legend of this rare Canonical character on a certain television program known for borrowing the occasional Canonical name and not much else. Perhaps our friend the KRM will spare him a demise from mere emotional trauma this time out.